There could be several reasons your laptop is getting hot. First off, laptop is a bit of a misnomer--they get hot and are meant to be used on a desk. Secondly, this laptop is a good 7 years old at this point, when was the last time (if ever) it had a thorough cleaning done on it?
Start with the basics and clean it out, new thermal paste, etc. Then if you are still experiencing abnormal heat issues (ie, burning your flesh), then there are some other issues at play here. If it is heating up after 30 minutes, though, probably needs a good cleaning.