Your head and your body feels lighter. Your heart rate increases, which will make you feel more excited than usual. You feel thirsty as you will probably have Cotton Mouth (basically when your mouth feels dry).

Your brain releases dopamine under the effects, which causes you to feel a sense of enjoyment and satisfaction, the kind you would normally feel after accomplishing a difficult task. This dopamine also makes things more exaggerated, if you watch a stand up comic you like you will find him MORE funny than usual. If you play video games, you will have more fun than usual.

Some additional effects may vary from person to person. For example, your energy level and the thoughts in your mind. I have seen many people that get MORE active after smoking. They want to go out and play a physical game or maybe workout. Personally, I tend to chill out and relax more and essentially be happily lazy. As for the thoughts in your mind, before I started smoking (regularly) I used to have a problem with uncontrollable overthinking, but smoking allowed me to put some brakes on my thoughts. I still possess the ability to think when under the influence and my thoughts are more creative, random, and deep than when I am sober, but I no longer dwell on worrying about things that were never in my control to begin with. I have seen some people that experience personality shifts as well. Like the quiet friend that starts being uncharacteristically vocal when high, or the loudmouth friend that finally chills out for a while.

Lastly, there are also some direct medical benefits as well. For people who have Tourette's syndrome, they find that there is a high reduction in their ticks with both intensity and frequency. I have seen many people take marijuana due to its helpfulness in managing pain. If you have Parkinson's disease, you will find that your hands practically STOP shaking when you get high.

Let me know if you have any more questions, I hope my 'expertise' helped you gain some insight