You can wake up one day and choose to be sad. There’ll be a voice in your mind that will say “you’re too thin”, “you’re not smart enough”, “you’re not the right colour”, “you’re not the right gender”, “you’re ugly”, “you don’t have any friends”…..
You can wake up one morning and choose to be happy. There’ll be a voice in your mind that will say “you’ve got your good health”, “you have a loving family”, “you have great friends”, “your job is actually really useful and helps people”, “you have a beautiful partner”, “you have all the money you need to live comfortably”…..
No matter what you think you can back that thought up. So you might as well choose to focus on the positive.