Sean Penn is very involved in the relief for Hurricane Katrina and the 2010 Haiti earthquake. After Katrina in 2005, Penn went to New Orleans to help the victims of then natural disaster. He was a part of the team that physically went out to search for those who needed assistance. After the 2010 earthquake in Haiti, Penn founded the J/P Haitian Relief Organization that helped set up camps to assist those in need on the ground.
Staying fit is certainly a commitment. Besides doing the physical training, there are some other factors to consider, like nutrition