Are athlete endorsements worth it? The answer may surprise you.

For professional athletes, endorsing brands and products is a second full-time job—and it sure can pay like one.

Patriots QB Tom Brady makes nearly half of his income through endorsements, while NBA star Lebron James gets 60% of his income that way. (For tennis icon Serena Williams, that number is 86%).

For professional athletes, endorsing brands and products is a second full-time job—and it sure can pay like one.

Patriots QB Tom Brady makes nearly half of his income through endorsements, while NBA star Lebron James gets 60% of his income that way. (For tennis icon Serena Williams, that number is 86%).