I gained about 50 lbs in my 20's by getting a sedentary job and eating poorly after moving out on my own. I spent a solid 2 years trying to lose weight by working out actively and lost nothing. When I changed my diet, I dropped it all over time and kept it off for the last 15+ years.

I tell people I know trying to lose weight to separate the ideas of exercise and diet, but few listen and most are quite resistant to the idea. To me, I think of exercise as maintaining a healthy heart, posture, etc. but keep it completely out of the picture for weight management.

The other side of this is motivation. If you don't see yourself losing weight from exercise, it demotivates you and that demotivation then carries into other areas like diet. So if you keep those separate, you won't make poor choices in your overall health as a result of feeling demotivated by the lack of results from exercise and you won't fall off the bandwagon so easily.