Don't try push-ups, by the way. You'll just get depressed when it doesn't work. I've found that the only people I know who can support their weight in the right way are the people who don't need exercise that much. It's odd that nobody else has pointed this out before, that overweight guys can't really do push ups.
Actually, pushups
aren't that hard...
if you take your weight into account and don't try to do standard Marine pushups at first. I keep my knees on the floor with my ankles crossed (
as opposed to behind my ears, you don't have to say it), and can do a few; I also use a bath-stool that has handles on the sides, and push up from there, it works a different set of muscles.
It also helps if you are holding on to something rather than putting your palms flat against the floor... at the gym they have these cool padded pushup handles, but I think you could jerry-rig some yourself out of PVC pipe from the hardware store for a tenth of the cost.
I hate doing situps, though. Booooooring! At least with pushups I can still watch TV. And I couldn't do a chin-up if my life depended on it, there's no
way my dainty typist's hands can support 250 pounds, no matter
how strong my arms might be.
But all these things should be done in baby-steps if you're in bad shape now. You don't want to hurt yourself. I found that doing a couple of pushups or squats while I'm waiting for the shower-water to get hot is a good way to pass the time. And going for walks is a perfectly good way to get started.
The endorphin rush doesn't happen until you manage actual cardiovascular impact, which doesn't happen until you've got your heart-rate up to... well,
some idiotic number that I can't remember right now.
If I was you, I would get one of those horny-making workout magazines. Not only are they very (ahem)
inspiring, but they have lots of useful information in them about getting started.