This will sound very dumb, but if I wanna feel happy, I put on my earbuds when I wake up, put on some happy music and I pretend I'm the protagonist of a movie and this is the montage scene that starts my movie.

Another thing is to treat yourself in the morning. When I used to still live with my parents, they weren't big fans of a nutritious breakfast, but I was. So I would wake up early to make myself a very nice breakfast just for me, the way I like it and watch a show or something.

Sleep 8 hours is essential too, it might not make you happier, but I will definitely help you to avoid feeling like crap.