And he'll be nothing if not in shape for the occasion!
Harry worked out at The Third Space, London's most luxurious gym, on Tuesday amid reports that his girlfriend, Cressida Bonas, was not invited to George's christening in order to help ensure that the matter at hand—baptizing the royal baby—would remain the focus of the day.
But though we doubt that Harry's feelings are too hurt, considering how versed he is with royal protocol, William's baby brother may be aching in another way.
After getting his sweat on, Harry then spent at least an hour meeting with a specialist at the Third Space Medical Centre, one of Britain's leading physiotherapy practices.
He left at around 4 p.m., local time—and we're told that he looked to be in good spirits after his session.
"He had a huge smile on his face as he left the gym," said a source. "His security guy was with him the whole time he was there, but other than that he just slotted right in like any other member."
Of course, the Soho gym's other members include the likes of Guy Richie, who's been spotted wresting in the dojo room. Professional rugby players Alex Corbisiero and James Haskel, and John Terry, former captain of the national football team, have also sought treatment at the medical center.
And tomorrow, Harry will suit up and join his family at 3 p.m. at the Chapel Royal at St. James' Palace for his nephew's christening. The Archbishop of Canterbury, the Most. Reverend Justin Welby, will perform the baptism and official photographs, to be released Oct. 24, will be taken at Clarence House following the service.