I got back on a bike 13 years ago at 270 lbs and I'd just stopped smoking b/c of cancer. I used to have to push my steel mtb up a lot of hills and it felt like my lungs would burst but I kept at it.

13 years later, at age 68, I have 2 road and 2 mtb bikes and I can climb every hill in Montreal. I've kept my weight at around 220-225.