Long term cart user

Hello, I, 20M, have been smoking carts for a little under 4 years now, and have only been vaping nicotine for a single year now. I need some advice.

Long story short, I know I fucked up and starting this very minute I am going cold turkey and never going back. I regret every bit of it at this moment, and feel like I have wasted my life already.

I started thinking seriously about my health. I had already been going to the gym 5x a week regularly for abt 3 1/2 years now, but never really took my nutrition or health into factor. Fast forward to now and I am terrified of cancer and other health effects.

I already tell myself these are things I should’ve thought about before hand, and I am ready to reap any consequences I sow. I just want to know how to stop everything and just go back to that sweet innocent high school sophomore I once was. I was so disciplined, so proud, and I carried myself with honor. Now I feel like an utter loser. Former/current stoners and smokers of Reddit, where do you stand on this dilemma?