Always feeling weak?

I am 23 years old, I work full time and exercise most days, my diet is quite poor I have to admit.

I am always weak and tired, always have headache, feel like sh*t most days overall I would gladly just sleep most of the days.

I just can't be bothered doing anything that is even just watching a movie. I "only" started feeling like this at the start of the year, I use to be a party social animal but now my friends practically need to drag me out.

Any advise on that?
Always feeling weak?
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