Recently, I have been really trired during athe day.

Present perfect here as it's an ongoing state. "I am really tired" would also be okay.

I assume that it is caused by spring fever.

I was going to correct this to "hayfever", pollen allergy. But apparently spring fever is a real thing? It's not something I'd ever heard of before!

I try to take a walks more than onean hour and eatlong, and take vitamin supplements.

Or "I try to walk for more than an hour". Using "one" is okay here but we'd usually use "an".

It's a bit strange to "eat" tablets, medicine, pills, supplements. They aren't food, and you usually "take" them.

However, thoese are not enough to overcome it.

This one is tricky. I think "those" is okay, and "this", "that", "it" would also work. But "these" seems most natural - they are indeed multiple things but they are also *your* things, things that you're doing, they're kind of "by you". So it's more natural to point closer to you with "these", "this" than it is to point away from you with "those", "that".

I hope my body adjusts to the temperature soon.

"to adjust the temperature" is more likely to mean to set the temperature control on your house heating system or some other system like that - the temperature is an object and it's being changed.

I think you mean that your body will get used to the temperature, and "adjust" is intransitive when used in that sense. So you need a preposition on "the temperature".