I only feel guilty after smoking when i have shit that i should be doing when i'm getting high.
I also sometimes wonder what my life would be like if i had never started smoking dope (i smoked through most of my years at school and without a doubt it affected my performance)
On the other hand i think of all the fun times, friends and sound people that it has bought me and then i feel glad that i chose weed as my drug of choice. At the end of the day, weed is a part of my life and if i hadn't discovered it i wouldn't be the same person that i am today.