Diet.
I know. Youve heard it before im sure, but im serious. Don't eat processed foods. Eat fruits, vegetables, whole meats, whole grains(rice, oats, wheat.) It's doable for cheap, and it makes such a huge difference in how you feel.
I'll give you an example.
Breakfast: 1 Banana+ a glass of milk + a teaspoon of coacoa powder. Blend it into a smoothie. Tastes amazing. Creamy, and chocolately, and its good for you too. Some combo of whole breakfast foods. Scrambled eggs, Fruit, toast, oatmeal, etc.
Lunch: pre-make pico de gello and have it in the fridge (Cut up cilantro, tomato, onion, mix it, and add lime juice.) Add a bit of that to a pan with a small amount of canola oil. Let it sizzle for a second or 2 then dump in a can of pinto beans. Give them maybe a minute to cook then smash them up with a fork. Mix in a spoon of peanut butter. Use that as dip for some tortilla chips. You can add shredded cheese if you want too.
Quesadilla, Sandwich, or wrap. Avoid deli meats. I like to cook chicken breast in a crock pot, and keep it in the fridge to use in stuff like this.
Dinner: Cook some rice about 25 mins before your meat is gonna be done. To the rice add the drippings from the chicken. Then add peanut butter. Black pepper, chili powder, etc to taste.
Chicken breast, or thigh or whatever baked+seasoned how you like to go with it.
This is just an example. You'll adjust it to your own tastes, and caloric needs, but the point is to avoid pre-packaged, and processed foods as much as you can. Also not mentioned was drinks. Drink water. 95% of what you drink should be water. A smoothie, or fresh fruit drink is fine too, but think of those as meals not drinks.
You'll notice i mix in things like peanut butter a lot. Not only does it taste good but its a cheap, healthy way to get calories. Milled flax seed is another one you can add to stuff easily. If your not used to cooking for yourself get some Salt, Black pepper, italian seasonings, basil, chili powder, and dried minced onion. Get your seasonings at ALDI if theres one near you. Theyre cheaper there (1$ a bottle). Just experiment with those ones a bit, and see what you like. Then introduce others and experiment more as time goes on. Thai Red Curry powder is amazing if you can find it but expensive.
If you eat whole foods for a week straight and don't start to feel better I'd be shocked. Other tips would be go outside, and let the sun hit you, breath in fresh air, etc for a few minutes a day. A morning walk can help a lot. Smells matter too. Get some like citrus skins, and simmer them in a pot to make your house smell good. Or cinnamon, nutmeg, etc works too. Just put things that smell nice in water, and let it simmer. Music too. Your mood reflects your atmosphere. If your in a place that smells nice, looks nice, and sounds nice you'll feel better.