When you train in the gym, you break your muscle down. When your muscle is repairing after your training, it reinforces itself and strengthens.
This is why recovery time is essential.
Fully recovered muscle is what allows you train with vigour and purpose.
That's the kind of training that gets results.
Fifteen to twenty minutes of vigorous, intensive, concentrated training will give power, speed and vigour to your body.
It will also train your body to be naturally relaxed, and your mind to be quietly alert.
So, do it.