By pushing ourselves from time to time, we increase our capacity. Looking at a running analogy, if I increase my pace a little at certain intervals, pretty soon my whole pace has increased.
In the world of production, once you try something for the first time, it now has the potential to be a part of my normal bag of tricks. The thing that almost killed you two Christmases ago, is now something you don’t hesitate to do on a normal weekend. Pushing yourself to try something new at the right intervals means that you are increasing your endurance, your capacity, your normal.
Pushing yourself too much or too often, will wear you down. However, without pushing yourself from time to time, you will stagnate.
Figure out the right pace for yourself. Then figure out how often you should push yourself.