In addition to what others have said about developing big time outlets for your energy, you could try something like body scan meditation to develop tolerance to and acceptance of sensations in your body while freeing yourself of the need to act on them. You could find some good ones on YouTube, I would suggest picking slow, detailed ones that teach you how to sustain non-reactive awareness of different parts of your body (including when you are feeling aroused). This is a great spiritual exercise in itself, and even more useful when you do it in combination with NoFap.
But yes, the real, pactical solution (unless becoming a full time meditative monk is practical for you) is to find other outlets that expend your energy and tire you in other, preferably enjoyable, ways. It could be running, swimming, playing music, traveling, whatever you like. If you have to make sacrifices of money or resources or routine or something else to make room for it, it’s worth it . That’s what the discomfort that you feel upon not fapping is really urging you to do. Go out. Do something. Anything.