Some Days are Harder than Others: WHY?

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You’ve no doubt noticed that whenever we encounter a potential disruption to quality training and the eventual realization of goals, we take a hard stop and ask two questions. 

Why does that happen? and What can we do about it?

We look at the challenge through three lenses:
(1) our own personal experiences (20+ years combined of competitive training disrupted only by a few notable injuries and for Andi, pregnancies),
(2) the experiences of our ever-growing community (friends, family, and all of you!), and
(3) our ceaseless study of the sport. 

We haven’t really articulated it thusly in the past, but that about captures the AtoZrunning approach. 

So when we reflect on the common shrug-off, “Some days are just harder than others,” we cannot help but ask those questions.

Why are some days harder than others?

My first comment on this topic won’t surprise you. The immediate and unfortunate answer to this question is that it depends. I’ll break down some of the most common reasons below, but at its core, the idea of struggle is both deeply personal and contextual and widely universal and absolute (by the way, we spent some time breaking this down more directly on this podcast episode). 

Consider the tension between perception and reality. Without trying to get too metaphysical, we know that perception influences reality in complex ways. 

And at the same time, it’s universal (I’ve been looking but as of yet haven’t found one example of a life without struggle). This tension of personal/contextual and universal at least allows us to examine potential causes, but always with an asterisk. That noted, if you find yourself struggling in your training and cannot find the cause, we would certainly love to try to help! Another opinion or perspective may be just the ticket!

For now, let’s dive into a fairly comprehensive list of those possible causes for your harder days.

Disrupted Routine

You’ve heard this from us before. Routine matters (think circadian rhythm, etc.). Subtle disruptions often produce painful ramifications. Consider these examples:

Time of Day

natural tendency

If you are comfortable working out at a certain time regularly, any change to that can result in unexpected fatigue, demotivation, or elevated relative effort. Daniel Pink writes about the science of timing in his book When, noting definitively that research indicates every one of has more and less productive and motivated times of day for things like working out. This natural tendency is cemented by routine, so if we do have a common routine for time of day, straying from it is that much more detrimental.

Location and Setting 

Do you have a preferred workout space? Andi commented recently on how she would rather run on a treadmill if it’s in an open area. Many of us share that sentiment. But it goes deeper than that. I have certain routes that I enjoy more than others. Anyone want to bet that I tend to perform better on those routes? (And it’s not because of hills vs. flat – I like hilly routes.) 

unfamiliar settings

It’s also true that unfamiliar locations or settings can either stress and demotivate you or inspire and energize you. Just look at any personality research out there. Likewise, unfamiliar settings require additional cognitive effort because you’re making more decisions than in a habitual and predictable setting. There’s a reason your high school cross country coach made you walk or jog the course before every race.

Emotional State

emotional status quo

If you missed it, go back and listen to our episode about Burnout and read this blog post. The key point that connects to this topic is the idea that our emotional status quo significantly influences performance. The psychology term is the hedonic treadmill.

Whatever the influence, positive or negative, our unconscious motivation is generally always pushing us back to that status quo (thus the term “treadmill”) often resulting in significant disruptions to our motivations, self-discipline, work ethic. Even if they’re positive influences. 

A friend recently informed me that he had a rough run last week and didn’t know why. Suddenly, later in the conversation, he realized that the night before that run, he had learned of the death of someone close. The difficult run at once made perfect sense.

Uncommon Activity

Have any of you (must be 30+ to answer) ever tried running after spending time at one of those trampoline parks? I don’t recommend it. If you follow me on Strava, you know all about that.

potential for soreness or even injury

Running is repetitive. This you know (think of all the marathoner caricatures and the size discrepancy of their legs and arms). Consequently, any activity that ventures outside that motion pattern is likely to present the potential for soreness or even injury. Why do college coaches fume at their athletes for playing pickup basketball? Sure, it’s an unnecessary risk of twisted ankles, but even more certain is the fact that all the cutting, jumping, starting, and stopping are at the minimum, guaranteeing soreness.

(And in case there’s any doubt, I side with the coaches on that one!)


Sleep volume and patterns matter

This one is self-evident. Not only does volume of sleep matter, but patterns of sleep matter as well. We spend some time on this topic in part 3 of our training guide if you need more convincing!

Mismanaged Training

For most of us, the above list of routine-related influences are easy to identify. The training category, however, is often harder to diagnose (and, as you might guess, is the area that we support the most often via consultations and general communication).

Balance of Effort and Volume

You’ve likely seen claims about the “right” balance of easy/hard running. In my experience, it is easy to misapply such broad generalizations, but the point remains valid. There is indeed a right balance for each of us, and operating outside that balance often produces frustrating experiences if not injury.

when the balance is off, things go wrong

Too much easy can be bad. Too much hard can be bad. Too much short can be bad. Too much long can be bad. The right balance has everything to do with the training goals and needs, and whatever the case, when the balance is off, things go wrong.

Underdeveloped Foundations

Certain things generally need to happen in a certain order. You need to be strong before you lift something heavy. In the running world, there seems to be a constant effort to prove that it’s possible to train in multiple capacities at the same time, but the fact remains that the bigger and deeper the base, the stronger the structures built atop it. 


Whether it’s true that you can train speed and endurance simultaneously does not suggest that it’s efficient or truly effective long-term. Too many of us try to do things in running that our systems simply aren’t ready to embrace yet. The results aren’t always bad and can sometimes even be good, but the inevitable will rise eventually. 

Attention to GSM

On the one hand, most of us do too little strength and mobility work. Many of the rest of us do too much of the wrong thing. In the end, very few of us are engaging in targeted, well-designed strength and mobility programs that effectively address our needs and move us closer to our goals.

move closer to goals

Deficient Nutrition

In general, this category is basically a sub-category of routine. Nutrition, at least in the short term, is as much a discussion about familiarity as actual health. However, it warrants a separate discussion because while we certainly strive to understand immediate consequences of nutritional actions, we also seek to develop enduring healthy habits.


We don’t drink enough water. (Read this for more – skip down to the part about hydration.)

Sugars and Fats

Our bodies need both of them for fuel (especially fats for distance running). As distance runners, our bodies tend to be more efficient when it comes to fuel storage and consumption, but with that efficiency usually comes a heightened experience with imbalances in our nutrition.

This is especially true with sugars and fats and happens to also be intimately tied to familiarity. For many of us, a healthy option that is entirely foreign to our system is just as bad as an unhealthy one, in terms of performance.

Vitamins, etc.

It’s not a bad idea to periodically get the blood tested and take a look at levels of vitamins, minerals, and nutrients. Most of us have one thing or another that is too low, and most of those deficiencies are proven to result in reduced physical output in some sense.

Health and Sickness

Things like core temperature and heart rate are significantly influenced by different kinds of viruses or ailments, even before significant symptoms appear, at times. I can win a battle with an oncoming cold and never know I was fighting it except for the fact that my training all but crumbled for two days.

Sickness impacts everything from blood flow to metabolization of fuels to inflammatory response and more. The dire reality is that even an imperceptible illness can derail half a week of training.

What can we do about it?

Read next: Some Day are Harder than others: WHAT to do?

You don’t want to miss it, since that’s really the practical side of this idea!

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