You could play with this, and make it a bit of a project, for fun.
Being a kind of fitness nut myself, I'd say "reducing my belly" is a part of being fit, overall.
Probably there are at least four components to having a flat stomach.
1 reducing body fat%
2 reshaping muscle
3 overall fitness
good luck, but I'd say it's more of a lifestyle choice, rather than a project with a start and end date