Yes it's possible to get healthy, although healing does take time. Two years of healthy living is adequate time to get really healthy. Many movie stars from the 70s and 80s did a lot of hard drugs, but have since changed their ways and gotten quite healthy. Drinking lots of water actually doesn't do much good, but instead try teas (like green tea), and juices (really healthy ones like blueberry, cranberry, spirulina smoothies, etc). Eat fish instead of meat, and use healthy oils like olive and canola. Stay away from deep fried foods. And marijuana is fine, but consider marijuana drinks like Bhang.