With all of the hard work it took to obtain your patent, the presence of infringers will undoubtedly rattle your nerves. The thing to remember, though, is that a patent is not protection in and of itself, but rather it is a weapon with which you can defend your invention and enforce your monopoly rights over it.
Unfortunately, it is difficult to stop patent infringement unless you first put the other party on notice. What this means is that you must first catch the other party in the act of using your invention and then let them know that if they do not stop, you will seek legal action. This is usually done in the form of a letter in which you acknowledge the infringement. If you do not want the infringer to do what you are doing at all, you can request that they stop, and you can also request an injunction preventing them from continuing their infringement. If you want to license them so you can earn royalties from you patent, you might need to just bring that subject up politely by inviting them to licensing negotiations or explore a business settlement. Sometimes none of those options work and then a patent holder must litigate. That is an expensive road, but if you have a strong patent or strong claim, there are plenty of success stories in that as well. In reality, it is difficult to sue. Litigation can also be very expensive. Therefore, probably the best way to move forward with the potential infringer is to first look into business solutions and negotiations where you can amicably resolve the issues at hand that you believe might result in a favorable settlement for you.