I don’t know, I feel like I should say some exam result or job achievement or learning something.. But really, deep down, my greatest achievement in my opinion is getting over the drug addiction I had last year without having to go to hospital or get hurt in the process. I had some insane willpower, and I went from taking drugs every single day to how I am now - Having my own flat, a decent job, and a loving boyfriend. 
And the meaning of life, in my opinion, is finding happiness in whatever you choose. It may take all your life to find the happiness, but you have to make the most of every opportunity.
Drugs is a difficult issue. I don’t believe all drugs should be legalised, because at the end of the day there are always negative side effects. I don’t even believe mephedrone should be legal, and that is a drug I do take. I just feel as though if it were made cheaper, it would be seen as more socially acceptable and I think it would make our workforce less productive. However, I do think there is enough interest/consumer base for weed that it may be economically viable to legalise. I hope that answers all your questions! :]