Gravity hates fat people. This is a fact. The older you get the faster you fall. This is also a fact (Well, no it's not, but it's an accurate description of the way perceive the fall.)
Whatever you don't give up. Don't ever stop riding. You have probably done this before, and you probably regretted that. You will regret it again. I would urge you to take up mountain biking, get a commuter or hybrid, ride the thing over the sidewalks(Do you have sidewalks?) Put it on the back your car or minivan and haul it a hundred miles to somewhere you can ride it on a nice decent paved country road or bike trail as God intended and not on some accursed boardwalk (Maybe it's just me, but a boardwalk sounds slippery and unsafe and I wouldn't want to ride on one.) get a unicycle and ride it up and down the driveway. Move somewhere you CAN ride every day, get a job there that you can commute to. Just don't quit riding.