Speaking in an ITV documentary which airs tonight, Prince Harry said it is "fun to be good" but "boring to be bad".
"If you're me, if you're your Average Joe, whoever you are, if you can't affect politics and change the big things in the world then just do whatever you can do - whether it's in your local community, your village, your local church - walking down the street, opening a door for an old lady, helping them cross the road.
"Whatever if it is, just do good. Why wouldn't you? The good stories are what make people tick every day, surely?
"It's fun to be good and it's boring to be bad, but you can be naughty as well."
The documentary follows the 32-year-old as he travels to Lesotho to work with his charity.
The prince co-founded the charity Sentebale - meaning "forget me not" - with Prince Seeiso of Lesotho in 2006 to improve the lives of the thousands of children and young people affected by HIV/Aids.
In the documentary, Prince Harry revealed that he no longer struggles against his royal role and feels that he needs to "make something of his life".
"I always feel like I need to make something of my life," he said.
"I was fighting the system going 'I don't want to be this person - my mother died when I was very, very young and I don't want to be in this position'.
"But now I'm just so fired up and energised to be lucky enough to be in a position to make a difference."
Prince Harry In Africa will be broadcast on ITV at 9pm tonight.