While many people have made New Year's resolutions to get in shape this winter, exercise is a yearlong endeavor for me. In truth, I'm a little fanatical about it. I don't feel well if I can't move my body for an hour — or two or three — every day. This routine doesn't guarantee lifelong health, nor is it the answer for everybody, but fitness has kept me relatively sane and focused in a constantly changing world where so much is outside of my control. It has worked for me — so far. Winter is tough. When most people are sitting down to dinner, I'm often heading to the pool. To trade the cozy comfort of my home for a cold car and dark night requires every ounce of discipline I have. Worse: As I age, the water feels chillier than it used to. In early December, about three-quarters of a mile into my laps, I thought: Maybe I should get a wet suit? That's how I wound up having a panic attack at Burlington's Waterfront Diving Center. The sole shopper on a weekday, I had hoped to find a synthetic rubber top with a front zipper, but there was only one style in stock, and it went on like a turtleneck. The male sales clerk gave me a "small" — flattering but probably misguided — and I went into the dressing room, stripped down and poured myself into it. The top was so tight I could barely breathe. How could I possibly swim in this? Fighting claustrophobia, I immediately reversed course. But in the process of trying to get the garment off — over my head — I got stuck. I was trapped inside a straitjacket of black neoprene with my arms, pinned to my ears, outstretched overhead. I thought about calling the guy for help, but it would have been spectacularly embarrassing for both of us. Instead, the adrenaline kicked in. I hulked out, stretching the wet suit just enough to get out of it. At some point during the contortions, I felt an odd sensation in my right elbow. A small price to pay for freedom, I thought at the time. I hadn't hit anything hard in the course of my struggle. Whatever I tweaked would surely right itself quickly. Maybe, that is, if I weren't four months shy of 65 — and getting texts…