A good walk might CLEAR MY HEAD.
CLEAR YOUR MIND: To stop worrying or thinking about something, or get rid of the effects of drinking too much alcohol.
She's always complaining that she doesn't have enough money, but WE'RE ALL IN THE SAME BOAT.
BE IN THE SAME BOAT: To be in the same unpleasant situation as other people.
The company is still doing business, but ever since the recession hit, they've been TEETERING ON THE EDGE of closing down.
TEETER ON THE EDGE (OF SOMETHING): To be very close to doing something or of having some imminent event happen, especially that which is bad or disastrous.
You're young and healthy and you have no commitments - THE WORLD IS YOUR OYSTER.
THE WORLD IS SOMEBODY'S OYSTER: You can do what you want or go where you want.
I sometimes think I'd be happier teaching in Spain. Oh well, THE GRASS IS ALWAYS GREENER!
THE GRASS IS (ALWAYS) GREENER (ON THE OTHER SIDE): Said to mean that other people may appear to be in a better or more attractive situation.