The thought of getting in better shape for summer never even occurred to me personally until I hit my mid-30s. I would notice that the pants were getting a bit tighter and I had probably actually gained 5 pounds (HORRORS!!!) .
So somewhere around the start of May, I'd just make sure I started riding my bike every day (or something similar) and by June I'd be trim and lean.
Now that I'm in my late forties, the over-winter paunch gets bigger each year and doesn't come all the way off anymore.
Time to adopt a new way of looking at this.
om