You know, I think this world would be a much better place if everyone would smoke a joint or eat a brownie once a week.
Yes. It DOES bring people joy. When I finally retired from the military, I did a whole bunch of research to figure out if it was as bad as what the Navy had told me. Well, after several months of checking out research from places like Harvard and the Royal British Medical Society, among others, and comparing it to what my DAPA training taught me in the military, I decided to try the ultimate experiment and try it for myself.
Been 420 friendly ever since. And remember.............pot will get you through times of no money better than money will get you through times of no pot.
As far as what kills motivation? In my experience, it is alcohol that kills motivation more than cannabis. Granted, if you smoke an high grade Indica, it will make you want to go to sleep (that's why they call it In Da Couch). However.............a good quality Sativa actually will give you energy and get you motivated for stuff like mowing the lawn, walking the dog, or doing some other chore that you find mundane and boring.
And, another thing that makes marijuana much better than alcohol is that you can get stoned off your ass the night before, and wake up the next morning bright eyed and ready to go. If you drink too much the night before, you are basically worthless until around 11 or noon.