How strong you feel and the high you get after a good workout; I attempted a year long couch to marathon training guide, only got up to running 7mi straight before I got sidelined by injuries, but after finishing those few long runs I felt so strong and I could see all the progress I made.

I also feel so much better mentally - part of that is being outside in the sun and getting that good vitamin d, but the other part is just the mental decompression that comes from the physical activities - whether that's lifting weight or going off on cardio.

Part of the inital bit is just forcing yourself to do anything, a good handful of my runs where slogs but I still got out and hit the pavement, everything adds up.

I still eat junk foods and chocolate though, in moderation. Intermittent fasting helps me control binging, and works out well when I'm mostly just maintaining. If I want significant weekly-repeatable losses, I count calories.

Tldr; it's less about motivation and more about self-discipline and perseverance. You gotta push yourself first to get that first high - which then becomes the motivation you chase.

Side tip: I'd recommend cardio kickboxing and zumba for anyone who wants to start out with something fun and can scale to various fitness levels - there is a large range of intensities. Check out your local community colleges and rec centers for adult classes; some even have circuit like strength classes using dumbbells and other equipment and are lots of fun. But like any form of exercise, you get out what you put in - you only short change yourself if you half ass it (but better to half ass than nothing at all)