Keep your pecker up
Definition 1 of 1
Pro Tip 1/3Cheerfulness in Adversity
Used to encourage positivity when someone is facing hard times. 
Your team may have lost, but keep your pecker up; there's always the next game.
Pro Tip 2/3British Origin
The phrase is primarily understood and used within the UK. 
Visiting London, he said 'Keep your pecker up' and everyone understood.
Pro Tip 3/3Informal
It's casual in tone and best used in informal settings or among friends. 
Don't worry about the rain ruining our picnic, keep your pecker up!