My horse Storm gets all stiff when I'm taking him out, so I think that we both just like to ride in the summer, better. The rest of my horses probably agree! It is fun to see the snow fly up when they're jogging, though.
I got a trick training book for Christmas and am spending lots of time with my horse on fun ground work "tricks". We're both having a blast doing fun, but valuable, things like walking/standing on lots of funky things, moving one foot at a time, and playing hide and seek!