If you wait to feel like acting before doing something that’s important, that’s not intelligent. You might end up waiting for a few thousands more lifetimes before you finally get around to doing it. You just need to act. When do you need to act? I hear you say, “Okay, I’ll do it tomorrow.” In America when we’re asked when we want something done, if we are in a rush we say, “I want it done by yesterday.” So if you are hesitant in aligning your actions with your goals, I suggest you start on your new behavior yesterday.
The act itself will later produce the feeling to act that way again. If a person who says, “I am too tired to exercise,” waits till he feels like exercising, he may never do it. But if he just does it, he’ll feel better and eventually will love doing it. The point is that often you are not able to think yourself into a new way of acting but you can act your way into a new way of thinking.
Regarding japa, for example, we want to build positive japa samskaras through regular good japa practices. Once we develop positive japa habits, our japa will naturally be consistently good. It will just be the way you always chant japa.
Motivation is what gets you going. Habit is what keeps you going.