Set yourself a goal
What motivates me to go out for a 16km run? The thought that if I don't go out and train, there will be more pain later down the line.
When we set ourselves goals, we provide clear and imminent motivation. Saying "I want to improve my health" provides little motivation as you do not see the positive or negative consequences for a long time. A goal provides you with a short-term, measurable outcome with consequences if you do not meet it. Just the kind of thing we humans need to force ourselves to make a change.
P.S. Happy Star Wars Day!