Can you change the colour of your skin? Tanning booths aside, nope.
Can you add six inches to your height? Not really, no.
Could you lose a few pounds? Possibly, but not overnight.
There are things about our physical selves that we accept. They're who we are, and how we look. So why then do some of us (including me) wish we could be different in other ways? We may pray that one day we'll wake up permanently happy, or less anxious, or more sure of ourselves.
The thing is, that's generally not going to happen.
Sure, you can work on your mind in the same way that you can on your body, but on the whole you're probably who you are, you know: you're probably not going to change that much.
Years of mood-tracking has shown me that I'll always have rougher times alongside my better ones. Knowing this and accepting it were two different things, though. However, it helps hugely - it really does - to be able to declare that you are who you are: there's a lot to be said for this.