Halfway through my Navy career, I became a Drug and Alcohol Program Advisor (DAPA), and was required to know about various substances, their effects both good and bad, as well as what continued use would do. Never in any of the research that I was given could I find anything that said it had a bad effect on the human body.
I also remember 2 smokers on my first ship (back in the early 80's), who got stoned on a regular basis, but they were always bright eyed and ready to work at 7:30 am, while the rest of us who had gone out drinking the night before were pretty much useless until after lunch because of hangovers.
Because of that, I decided that when I finally got out of the Navy, I would try some of this cannabis stuff that people had talked about to find out for myself.
Spent the next 6 months after I retired researching just about anything I could get my hands on concerning marijuana to see if I really wanted to try it. Figured out that I did, and started smoking, and found out that I liked it much better than alcohol because I didn't get as stupid, and never had a bad morning after.
Then, when CO legalized it for recreational use, I started going up there and trying all the different varieties that they had and found out that while I'm willing to smoke just about any kind of marijuana, I really prefer Sativa strains.
Yes, I smoke, and I'm not ashamed of it. It seems to do a lot more good to me than it does harm. And, when I have sore muscles from working hard, smoking a bowl or two of Indica does great for pain relief and makes it easy for me to go to sleep.