I make it a PRIMARY goal to NOT give myself any negative messages about my body: what it looks like, how much fat it's carrying, whether it seems bigger or smaller on a given day. I firmly believe that a body can only change from a place of love and acceptance...and if I can't conjure love and acceptance, then I at LEAST don't let myself descend into negativity. If I find myself feeling fat or ugly, I tell myself, "That's how I feel at this one moment. This moment is not forever."
I remind myself all the time that mirrors DON'T have absolute power -- for example, think of how many times you've looked in a mirror, HATED what you saw, then turned a fraction of a degree and told yourself, "Oh, phew! That's better!" What we see in the mirror is totally malliable and subjective!