Once you master a particular movement, such as a squat or bench press, the nerve cells in regions of your brain that control movement develop stronger connections that make it easy to jump back into the exercise even if you haven't done it in a while. The same happens with other movements. For example, if you jump on a bicycle after many years of not riding, you may feel less confident, but you can still ride. The connection between neurons, or nerve cells, that control that movement is still there. So, you can jump back on without learning to ride a bike again, as you had to in grade school. It's reassuring that once you learn to ride a bike or do a particular exercise, you don't lose it every time you stop doing it. You've built a template that your brain and muscles use to get you back up to speed fast!