If more people got out in the winter and had as much fun obesity rates, particularly in the Midwest and other cold, fat states, would take a serious hit. There just isn't a downside to getting out there.
But I digress. A short time back I contributed a tip to TMuscle's ongoing twitter series. This one concerns using the muscles and tissue in the upper back/thoracic area to build strength and improve posture all at once.
The next time you do one-arm overhead presses with a kettlebell or dumbbell, try using thoracic extensions for increasing strength. Just before you begin to press, round your upper back slightly, then as you start to press, stick your chest out and pinch your shoulder blades together forcefully. Do NOT arch your lower back, but concentrate on your upper back. This will not only allow you to lift heavier, but has positive effects on thoracic mobility and posture.
There are some other cool ideas in there too so give the whole article a read.