When you can't convince people that Knack 2 is the GOAT.

When school is stressing me I usually take a day off, go to a park, lay on the grass and listen to some music. That usually helps me get back to the routine, though it might be difficult for some to just randomly take a day off

I'd get that checked out because your insomnia might be contributing to your stress or your stress is preventing you from sleeping.

I did nothing

Depends on the situation. Watching a film I really like, listening to music and reading a good book, playing video games I like, or a number of other ways. I find that there really isn't one good way to do that. I just go by how I feel like at the moment. For example, it may be quite odd to a lot of people, but playing Dark Souls is a really good stress relief for me at times. Probably because overcoming a really difficult challenge is a great feeling in general.

I would say exercise. But Sleep is by far more important. If you do get some more sleep, your exercise will feel much much much better. Finally if you do decide to go exercise do not feel like you have to follow the program someone put up, you can do the exercises you want and be good with it. Just make sure to not injure yourself or develop bad habits.

Other then that...

Last night I was stressed and depressed even after I worked out. I fixed it by laying down for 30 minutes and destressing/meditating/thinking about it. Immediately after I got some good food and ate it, and went on to do my work.

Good food is always a good destressor.

Also a really funny show or video might help like: https://www.youtube.com/watch?v=xa-4IAR_9Yw

Lastly if you have been depressed for a very long time due to monotony. Use some of your money and splurge on something or spoil yourself with something. I spent $45 last month on things entirely unnecessary and it gave me a temporary rush of happiness. Just don't go overboard.

Writing, writing, writing and writing a lot of nonsense.

Eating grapes helps too.

Hmm, your case sure does sound complicated, with lots of "if"s and "but"s. From what I've read so far, the major things I would recommend (such as physical exercise at the gym) are things you've already tried to little avail. When I went through a bad patch, I found that the gym didn't necessarily help change my mood at the time I was in the depths of it, but it helped me out -a lot- when I started to cross some sort of threshold as I left those depths. While in the depths though ... For me, binge-watching TV shows helped distract me a lot and I really found that work of all things, at least for me, gave me significant focus and distraction. I also got pretty bad sleep when I was in those depths too ... Probably a whole 1.5 hours less per night on average. It would say they're quite coupled for me indeed.

Everyone is different of course, so I'm not sure if my experiences can translate to help for you :( Upon reflection, I found that I used things like gym, binge-watching great TV shows, working hard etc. all provided distraction for me to at least keep functioning as a normal person. I just kinda had to wait until something else came along, to help change my circumstances further (maybe a change of scenery or sorts) and cross that threshold, when the positive effects of everything began to compound more and more.

You owe it to your own mental health to splurge on something, preferably not video games though since you got that down on lock.

Maybe a nice date at a restaurant. Maybe a new shirt. Maybe dual exhaust for your car. Maybe something imported. Idk.

Also to change monotony, move around your furniture, make it look new. Maybe even if your bed changed places, you could sleep easier. You never know until you try. Also of course when you get the money, get a new mattress :P.

People keep saying sleep but that can be counter-productive. When you're depressed sleeping can become an unhealthy comfort, where you end up sleeping around 12 hours or fucking up and sleeping a lot around 5-6 which makes you stay up too late. I remember before I left school I'd just come home and go to sleep.