How can I be happy? I swear I've tried. I've tried

Have you tried meditation?

We often want to run away from our thoughts because our brain is hard wired to constantly think about past regrets or worries over the future, that we forget to just sit there and take in the present moment. Meditation may help you with that.

>>18081070
Persistence.
You've already made efforts towards happiness, which is commendable. Many like you haven't had the strength to do even that. But just keep on doing what you're doing. Depression will make everything seem forced, but try to differentiate between things your sadness is sucking the life out of, and things even a happier version of yourself wouldn't enjoy. Change your habits accordingly, and happiness will come easier.
Addressing the issue and starting to work to solve it is the first and hardest step, and you've already accomplished that, keep going

>>18081070
When do you think did this current episode of you feeling bad start? How did it start? Was it a slow developement or did it "switch" within a day/week? Did something happen beforehand in your life / did something change?
When was the last time you felt healthy?
Have you felt the way you do know before? When? For how long? Was it like this time, better or worse?

Are you sad? Or do you feel empty/ unable to feel anything at all?
Can you rejoice over anything? Do you have fan when doing hobbies?
Did stuff you did before become harder? Do you feel exhausted?
Do you feel guilt? Do you spend a lot of time brooding without reaching conclusions, are these thoughts repeating?
Are you tired of life? Do you have suicidal thoughts?
Do you have sleep problems? What kind: Falling asleep? Sleeping through? Is it hard to get up? Do you wake up way too early, can you fall aspleep again? Is your general situation more bearable as the houres pass (evening, night)?
How is your appetite? Did you lose weight?
What's your sex drive like, is it reduced?
Do you have other body symptoms?
Do you feel inner restlessness / unsettledness ?
Are you afraid of certain situations or objects?
Are there things you have to do with so much diligence that it gets a burden for you? Are there thoughts obtruding your mind which you percieve as senseless?
Do you sometimes have the feeling there's something wrong or strange with the world or your body? Do you feel like others want to harm you, like they watch you or like your thoughts are being controlled or read?

Was/is someone in your family affected by mental problems? Were there suicides in your family?

Answer above shit, I will give you a corresponding diagnosis and tell you about treatment. Exercise is helpful with mild to moderate depression, but I would suggest further therapy. There is no need to "serve" an episode of depression. It's a "real sickness" like cancer that has a "real" foundation in the body. And there IS treatement!