The problem with your weight is not that you’re not exercising, it’s what and how much you eat.
You can be slim or normal weight and happy by not exercising a day in your life. This is because how you look and feel is 80% influenced by what you eat and drink.
It’s incredibly hard to out-exercise bad eating habits, I tried to live off steak, fries and cake, it ended up with me being anemic and chubby. Then I went on a healthy diet and remained chubby because I was eating too much.
However, exercise is what determines your body composition(muscles, fat, bone % etc.) and how you look.
Here’s an example of the same person, same healthy weight, same height, one not exercising and one exercising.
The type of exercise you do also influences how you look, here’s what a marathon runner looks like compared to how a sprint runner looks like.
80% diet and 20% exercising, so put most effort in healthy eating and drinking in sensible amounts and you’ll see better results and won’t be exhausted.