I started again last year (late February or early March), weighing in around 325. First ride was about 5 miles and I was a little tired but could have kept going. Next 3+ mile ride was a 14 mile RT to my office on a weekend as a commuting test run. I was tired, but I realized I could do it. My weight's down to right around 300 now (hope to see a 2xx on that new scale w/in the next week), and I feel healthier than I ever have since my senior year of high school (when I played varsity tennis and weighed in at 235.) Now I make a 14 mile RT commute daily by bike and usually wish it was longer. I occasionally go out for longer rides, too. Longest has been a little over 40 miles. Hope to do a metric century by my birthday (in June) and be down to 225ish by the fall.

Long story short, it may hurt to begin with, but keep at it. It gets better and a whole hell of a lot more fun!