Sheer sleeves will surely keep you motivated to work out this Fall. In fact, I can't think of a better way to show off those hard earned toned biceps. Daring slim sleeve cuts, like this racy Derek Lam Zip Front Dress ($1,650), emote a more '80s vibe while billowy romantic sleeves, like the one January Jones recently wore allude a more modern aura. Take your pick . . .