I'd point out that at least in aerobic exercies (ie running and biking) its generally recommended that you shouldn't be pushing too hard for most of your workouts. If you're going out four days a week it's only on one or two of them that you're generally supposed to push yourself. The others should be at an easier pace. Which I tend to find more enjoyable.

There's also something to be said for seasons of maintaining a level of fitness rather than pushing for the next level!

https://stories.strava.com/articles/a-productive-weekly-trai...