I am 20 and I have been smoking for three years. What are the risks I have gained till now, and will I overcome them if I quit now?

Here is how you can totally overcome it in my understanding:

What you must actually give up is the idea that you can’t create perfect health. Don’t let ideas about having smoked diminish your life force energy. Ultimately, there are no risks, because there is no chance in life. Everything is created by us. Don’t leave things to chance. Don’t fall asleep and empower thoughts that suppress or scatter your life energy. Awaken to this more and more fully.

This is a very core level teaching but I feel to remove doubts 100 percent, we must awaken to the core level truths: More Important than Anything You Do or Create is the Experience of Yourself

What I am saying is that, more than what you have done up to now, how you experience yourself right now is the determining factor of how healthy you will experience yourself in your remaining life. And I am learning this too, that how we experience ourselves in this moment can be degrees of empowered and capable beyond our imagination.

I will also mention a story I heard about Krishna’s drinking milk from poisoned breast and not being harmed.

Krishna and the Women in His Life

I will add to this that all is one and what Krishna is, we are too, though we may not be fully awakened to this. So, may you start remembering your capabilities, and live your life accordingly, if this is what you truly desire.