OK, I walk to work and back three times a week (Good because I both save on car parking charges, and don't worry about some little scrote damaging the car). I take a change of clothing, and can shower at work if I really have to, but I hardly break into a sweat any more.
I never eat after 7.00pm, it can't be good going to sleep with all that sludge lying heavy inside you. I also drink half a litre of water before bed (Some say it makes you pee all night, it doesn't me, but it might others, so if this doesn't suit you, then don't of course do this).
I also lift freeweights a couple of times a week. This can lapse, but I've recently gone back on to these. This is very helpful if you are a guy, because after you reach your mid 20's, you start to get muscle atrophy, and as you lose muscle, you gain fat, because muscle takes a lot of energy to function. That's why many guys over 40 have beerguts.
Lastly, I jog just around the block (About 800 metres) each evening. Running is a great way to keep the fitness up, and although this hardly makes a difference, every little counts as Tesco says. If you make it brisk, you know how fit you are by whose house you start panting at