The 80/20 rule... although it is more 90/10 for me.
For example, being full vegan is awfully hard (at the start), but eating vegan 90 percent of the time is actually super easy.
Biking instead of driving most of the time is much easier than telling yourself to cycle every day.
We often treat things as all or nothing... And sure, I'd love to be perfect at all the things I find important, but doing so puts certain things out of reach because it makes me frustrated and give up on good intentions.