I think it’s hard to deal with sadness and anxiety because usually when you feel that way, it feels all-consuming. But it’s just an emotional state, it can try and control your day and you have to really try not too.
Accept you’re feeling terrible. Be in anxiety, jealousy, anger, grief or whatever you’re feeling.
Decide whether you can deal with it today by owning your problem and pushing through with it with willpower or company of friends or whatever else might comfort you.
If it’s not today, accept you’re giving it rest and you’ll deal with it after that rest.
Resume focusing on being happy.
I’m not lecturing any of you on how to be happy, that’s not exactly my expertise, but writing this and reading it back has already made me feel better, so give it a shot, perhaps.