Doing for those that are not physically able to do it

Motivation get you started but discipline keeps you going!
.
Motivation is prsenting yourself with the exact reasons and facts that make you think and work only in one direction. It is something that makes you think in a positive direction and pushes you to adapt good habits which is actually very difficult to achieve with your daily activities.
.

Discipline is a foundation for understanding consequences, making behavioral decisions, and establishing lasting personality traits.

Discipline allows you to achieve goals by weeding out the distractions in your life. ...

physically