Prince Harry Getting Fit for Homeless Kids

Prince Harry doesn't want kids in the UK to go without a roof over their heads ... so he's popping a squat and breaking a sweat to make sure that happens.

Harry went into full workout mode Thursday with members of The Running Charity in London -- an org that raises money and helps homeless youths find housing and stability.

He's clearly serious about the cause ... as seen in his impeccable form. Well done.