i know it can be expensive but if you can try buying organic. get leafy dark greens and vegetables. cut out ALL processed foods. lower your Sugar intake. i dont buy everything organic because i dont have much money but when i can i do. just work on gradually improving your diet.
i was perfectly healthy too and had a lot of energy, very active and loved to play sports. now i barely want to get out of bed.
remember one thing: you still have your mind and the mind is the most powerful tool