For a few weeks now under my eyes are always swollen, especially the left eye, no matter how good i sleep it doesnt go away. i drink sufficient amount of water between 3 to 5 liters of water, workout at the gym, eat healthy with low amount of salt?

Swollen eyelids (I think that's what you're referring to) can be the sign of many different things. It could be as simple as the side of your body your sleeping on to inflammation (allergies) to too little sleep to cancers (unlikely) to thyroid disease. If it doesn't improve, see an ophthalmologist

You may have ocular allergies. Try using Zaditor or Pataday over the counter and use a few pillows at night. Another common condition is benign angioedema — swelling of the eyelids that occurs primarily at night. Call your local eye doctor if symptoms persist.