You don't need to be 'doing the gym' mate - actually, despite being quite fit and active, I hate the gym, I'd rather be out in the fresh air cycling or walking. Just having a walk in a nice area every day where you just get a little breathless is a good start. I'm fortunate where I live, I have the Brecon Beacons national park on my doorstep 
It's always worth losing a bit of weight if you're that heavy, your everyday life will be so much easier. It's never too late, it can be done. Best of luck
True that - I fished the bike out of the garage this weekend .. not convinced the wheels will hold my weight, but I bet the steel frame will. Might need some air in the tyres first, though

Also spent the entire weekend getting very out of breath working on the house - beating the remains of a wall out of the ground, digging a rhododendron out, building a new wall & door on a lean-to shed.. oh and digging a big chunk of flesh out of my head when I walked into the edge of the metal shed

still, all good exercise (and my head finally stopped bleeding without needing stitches

)
On the success stories front (following on from Webby) - there was a bloke recently in the US who lost 400lb and had a really inspiring story..
http://www.oddee.com/item_96622.aspx - second one down (David Smith)