I am a guy,30yrs, want to flatten my lower chest. please advise some best excercises?

crunches, running, hang from a bar by your legs (if you can) and curl up. do as many as you can, as you go youll get better and better and itll tighten everything up. this you may not be able to do but if you do 100 situps/crunches it tightens your abs for 2 hours and if you do it everyday itll become longer eventually itll stay. also just some advice to stop annoying craves for fatty food etc. if you exercise you have an hour after that your body will use fat as energy, after that hour your body starts storing food as fat again ^.^