Tom Brady could far outearn every NFL player in endorsement money, but he chooses not to.
The average person puts on around six to eight pounds when they quit smoking. Some people may put on more-even up to 30 pounds. Most people return to their normal (pre-quitting) weight after just one year. But, you would have to gain almost 100 pounds to put the same pressure on your heart that smoking causes.
There are no 'side effects' per se when you quit smoking cold turkey, but you can expect significant withdrawal symptoms from nicotine. In other words, unlike quit smoking drugs, or patches or nicotine gum, there aren't any negative effects from the method of quitting.