Depends on how much you smoke it. If you smoke frequently, it impairs the body's natural ability to relax, and it can affect muscle tone and reaction time. Smoking only occasionally can make you feel relaxed, sleepy, and hungry, but does not tend to have long term effects. Smoking on a frequent basis will affect the brain's ability to concentrate and reason through ideas quickly, and eventually, it becomes hard to feel relaxed and at ease without it. All depends on frequency of use.
Some effects of marijuana include: aggression, anxiety, depressed mood as well as decreased or in some cases increased appetite. Physically, marijuana leads to distorted sense of time, paranoia as well as short-term memory loss. For more information, check out http://www.webmd.com/mental-health/marijuana-use-and-its-effects.
Smoking weed is great if you want to give yourself depression, breathing problems, hormonal imbalances which result in men having man boobs, low sperm count and many other great benefits from smoking dope.