I think if you enjoy helping others, you should become a firefighter. By becoming a firefighter, you are showing others you care on a daily basis.
There is significant risk involved, and firefighters are trained to make quick decisions when faced with dangerous situations.
Keep in mind that firefighters don't only respond to fires, however. They spend a majority of their time responding to other emergency medical calls.
If you are considering becoming a firefighter, I think it is also beneficial to consider becoming an EMT or Paramedic.
I want to add, while the above are all pros there are still some major cons. You will respond to and see some of the worst accidents imaginable. Firefighters play a special role in society, we face those issues that others cannot.