Exercise is the healthiest way to lose weight, but it is basically ineffective if the intensity and time are not guaranteed. Like a hula hoop, it takes at least 40-60 minutes and 2-3 months to see the changes in your body. On the other hand, if you don't insist, of course, there won't be much change in a month.
In addition, you need to strictly control your diet. If you exercise, but you can't control your mouth, it's equivalent to eating more than digesting.
If you want to lose weight in 3-4 months, you have to consider other factors comprehensively.
Too many words, one word is too much trouble. Let me show you an article: "Mu's Six Years and Losing Weight", which is very comprehensive and may be helpful to you.