eli5: Why do we always get strong urge to be lazy if its better for the brain to be active

Question

I mean its so much better for the brain to be active working doing useful things stimulating your brain or working out, we all have a reward system and everytime we finish a task we feel a sense of accomplishment but everytime you should be doing something that you know will feel good in the end you just get this urge of doing nothing today and just relaxing,
shouldnt our brain be chasing this sense of accomplishment? Where does this feeling come from

In: 7156

Answer 1

When your body has everything it needs, doing nothing is usually the best course of action where best is defined as least chance to die.

We evolved from contexts where being overweight was a pipe dream so gaining weight and the multitude of health risks from that were non-issues.