I smoke mmj for PTSD. I also take anti-depressants from VA. I have bad paranoia and anxiety when I go into busy places. Sometimes the local grocery store is too much to handle. I also have a hard time sleeping, with nightmares and restlessness. I specifically asked my Physiatrist to prescribe me something that won't make me a zombie. I tell him about my mmj use and talk to him about how it helps me and how I use it instead of other drugs with way worse side effects.
As long as I have the right type of smoke, just a few tokes from the pipe and I'm good to go anywhere for a hour or so depending on how strong what I'm smoking is. If I'm going to be out longer I sometimes smoke more, but I find that overindulgence in the day makes it hard to remember what I left the house for.
If I have the money or when my garden is harvested, I'm able to have more than one type of smoke. This is great for me because sleeping is really hard for me to do on most nights. If I have a nice powerful indica, I can usually take a few hits and fall asleep quite fast. On these nights, I tend to sleep virtually dreamless and it's great.
The biggest problem I have here is that even though I live in a legal state, and have a recommendation, there's no dispensary in my area so I'm stuck smoking what ever is available with no variety.
Hope this helps.