My relationship with weed before and after 25 is so different. It has to do with age and growing up too, obviously, but at 25 I was diagnosed with crohn's disease, albeit a mild form compared to some others I read out there. Before then, I just smoked for fun. Getting high, listening to music, watching movies, going to town on munchies, etc etc. Only smoked occasionally, so every time, it was truly getting stoned, which was fun.
After I got crohn's, I went on all these different meds, each with their own side effects. Also, if you ever get a flare up or "attack" as I like to call it, it's unbearable. You'd need to go to the ER to get morphine. I was living in Washington state at the time, and they had a very strict medical MJ program (much much stricter than Cali's, although it's straight up legal now in WA), but I read about it, and it was prescribed for like 4 conditions, most of them being serious stuff like cancer, but also crohn's. I can't even remember the first time I smoked when getting a flare up or attack. And it's not as effective as morphine, obviously. But it truly dulls the pain, I think by relaxing abdominal muscles, which cramp up during a flare up, kills nausea, which is terrible during an attack, and basically allows you to rest, sleep, and regain your appetite. It was like tailor made for crohn's disease. This is when weed to me stopped being just a fun thing to do. It has so many life applications that I'm like a total cannabis endorser/promoter to everyone I know now.
So now I smoke pretty much daily. I also have always had trouble sleeping, so obviously this helps a bunch. I do like that it's introspective, even when I get "negative" thoughts because that's just me confronting issues, which is good imo. Weed's helped me bond with friends and family.
The only potential negative is that I do feel psychologically dependent on it. But then again I'm a very specific type of smoker. Though I smoke pretty much daily, it's a routine for me, usually an hour before bed or so when I wind down, and then for the very rare crohn's attacks. Going back to crohn's, I read this study they did in the UK where they found that weed reduces inflammation. I have no idea if this is true, but since I was diagnosed and started toking daily, I live pretty much in remission.