Not-so-great runs happen to everyone.

When they do, it’s a good idea to check in on key areas like nutrition, hydration, sleep, and stress levels. For example, if you ate your usual amount after a long run instead of slightly increasing your intake to match the extra effort, that could leave you feeling off. Similarly, a few nights of poor sleep or an increase in life stress can also take a toll on your performance and recovery.

All of these factors can quietly add up and impact how you feel on your runs. That’s why it’s worth pausing to see if any of them can be adjusted or improved. But if everything seems in check and it was just one tough run in the midst of many good ones, try not to overthink it—chalk it up to a blip and focus on setting yourself up for a better next run.

However, if you start to notice a string of difficult runs, it may be time to take a closer look. That could mean backing off your training a bit, getting a blood test to check for things like iron levels, or consulting with a healthcare provider to rule out anything more serious.

If most of your other runs have been good, don’t put your focus on one bad run. You’re not losing fitness. Shake it off, be supportive of yourself, and set yourself up to feel better the next day!