How To Solve Microsoftnokialumia 730 Heating Issue.

I recently bought microsoftnokialumia 730 and had been using it for five days. Now the issue is that my phone gets too much heated very quickly. It gets heated on both rear and front sides, and this happens over minimal use too.
For example whenever I browse like for 15-20 minutes with no app running in the background, and after some time it restarts automatically. So can anyone help me solve this issue?

