Well, it is common that marijuana allows your mind to focus on things from a new perspective and reduces the extraneous and unimportant stuff in your brain, “opening” your mind. I’ve begun recently medicating with it and it helps me too! You might be holding a lot in and keeping your brain ‘stiff’ in its habits in order to cope and weed reduces this anxiety. With the anxiety gone, you can see other options, possibilities because you’re thinking and observing from a more objective state. That’s why you have these revelations and clarity. That is the oft-noted effect of marijuana.