I agree, being happier takes a lot of work. That in itself is sad, but I can accept it.
I actually had CBT last year for 10 weeks. Although it may not have helped much, I think one or two things did stay in my mind, and maybe still help me now. When I'm back home I will call up the therapist and ask for more. Just one more thing which perhaps can help.
My food regime is good. My sleep is ok. I used to exercise a lot but recently stopped.. probably part of my falling back into another deep episode of depression.
Consider talking to a doctor about medication. I have no medical training, I'm not going to advise on medication. But there are different types of medication. There are different types of anti-depressant, and there are anti-anxiety meds.
While you're doing that you might need to put in some work on building up resilience. This will include support networks of people to socialise with; education and work stuff; exercise; etc. It'll include getting your food sorted out, and your sleep hygiene.
Expect to put in a lot of work.
But good luck!