It's normal that you may have some difficulties when you start fitness, or you may want to give up, but as long as you stick to it when you want to give up most, you will find that there are still many things you can do and a large part of your potential has not been tapped. You can set a timetable for yourself at the beginning, and urge yourself to exercise at that time every day. It will be much better if you stick to it for a while.
My summer fitness is to lose weight. At first, I will do a whole set of training every afternoon. It was really difficult in the first few days, and my legs were too tired to lift, but when I thought of myself after losing weight, I somehow got the motivation and gritted my teeth and continued to do it. I really wanted to give up a few times before, but I persisted in order to better myself. After that time, I feel very happy to exercise every afternoon, probably because of some small achievements, and I am not so tired to exercise every day. Now, even when I have my period, I insist on doing some exercise, as long as it is not particularly intense and I don't want to interrupt the exercise.
You should first find some reasons to keep exercising, just like I just want to lose weight and look better. After a period of exercise, you will find that you don't need those reasons anymore, but exercise will make you feel very happy. In fact, to form the habit of fitness is to stick to it in the first few days. After that hard time, you will naturally form a habit.