A couple of Christmases ago, what with one thing and another, I didn't get to the gym over the holidays. By the end of two weeks, I was climbing the walls, convinced I'd lost all my muscles and put on loads of fat.

He told me it just wasn't possible. It just wasn't possible that I'd lost all my muscle in 2 weeks and it also wasn't possible that in one session I could have got back what I thought I'd lost.
The moral of this story is this: it really isn't about what you actually look like, it's about how you feel about yourself when you look in the mirror.
If you look in the mirror on a day when you feel have accomplished things, you will always see something better than what you see on a day when you feel you have achieved little.

Regular exercise boosts immunity, self-esteem, metabolism and mood - it also radically improves what you see in the mirror, simply because exercise makes you like yourself more.
When you like yourself more, it's easy to smile at your reflection!