I walk. I do the treadmill; I walk around the mall. I do a little crunches with my stomach, not that much. Just enough to get the engine going cha-cha-cha-cha-cha-cha! Vroooommmmm.
I do abs every day: regular, weighted crunches and sit-ups every other day, then my obliques and my sides on the alternating day. So I'm working my core every day.
If you think you're going to do 100 crunches and a plank and burn away belly fat, you're not. Yes, you're going to make the area stronger, but it's not going to get rid of the fat. So do yourself a favor and, once and for all, let that idea go.
There was a massive poster of me down my road, right outside the chip shop. I was about to go in, but then I saw it and changed my mind. Me coming out with a bag of chips, while I'm up there doing crunches on the poster... well, it would not look good.
You can do crunches all day long, and you abs will indeed get bigger and stronger, but you will never see them. The only way to see the muscles you work so hard for is to lose weight globally - across your entire body.
I'm not fond of crunches or lunges, but I do them anyway because I do see results. For me it's about being fit and staying healthy more than anything else.