Benefits of quitting cannabis

Over 30 years of smoking, now 2 days free, this is the biggest battle I have to win. I gave up heroin when I was 18, cold turkey and have never touched it again. I was hypnotized (to give up pot) 15 months ago, when I reached this same point  of self loathing, and it worked for 14 weeks 3 days (yes I was counting) then I had a bad day at work, went to a friends and had a bong, that was it I was back on it again and smoking every day. Today after 2 days of not smoking I feel dreadful, am experiencing headaches, crying, anxiety, nausea and constant feeling of shame. I am having an internal battle with myself but I know the only way I am going to improve my life is by giving up. I feel like such a loser after having so much potential as a young person and wasting so many opportunities because of weed. Hopefully by being a part of this forum I can stop this life long habit and find self motivation and strength of mind again.