What are your thoughts on me avoiding my friends because they smoke?
How does their smoking make you feel?
I feel bad about it because I'm their friend and but I just see them wasting their time.
I understand your view. It may be helpful to talk to your friends about how their smoking makes you feel. They may respect your position and avoid smoking around you.
I just don't them to go overboard with it when we hang out.
It would be good to discuss this with your friends and explain to them how that lifestyle personally affects you.