Regular workout is a basic need that everyone should incorporate in their regular life to maintain healthy muscle mass and function. Muscles that are not continuously challenged will grow weaker, even weaker beyond the minimal need to support basic activity if we allow it.
Life is like climbing a mountain. If you stop, you put yourself in danger. The older you become, the steeper the mountain. Your body is very smart and flexible, but it does not like to spend energy there were not needed. Anything that is not continuously challenged eventually grows weaker. Keep going.