Princess Charlotte is a "very easy" and "sweet" baby but father William said he is preparing himself for drama as she gets older.
The Duke of Cambridge spoke of his nine-month-old daughter and son Prince George, two, at the Principality Stadium in Cardiff ahead of the RBS 6 Nations Wales v France game.
William, vice royal patron of the Welsh Rugby Union (WRU), chatted to players who have been severely injured while playing rugby union in Wales.
He is patron of the Welsh Rugby Charitable Trust, which offers practical support as well as pastoral care and social opportunities for the former players and their families.
When asked about how his children were, William replied: "Very well. No broken bones so far but they are trying - running around and pushing things and jumping.
"Please tell me it gets easier. Charlotte is very easy, she is sweet.
"But all the fathers say to me 'just you wait, when they get to nine or 11 they get crazy'.
"I'm looking forward to it. There will be some drama."
William revealed that his job as an air ambulance pilot is "good, different", adding that he finds the medical side "fascinating".
The Duke spoke to Frances Bateman, 34, a former player for Gwernyfed in Powys, who previously showed him a copy of the team's 2015 nude calendar.
She asked whether he had been in trouble for looking at the calendar when they met in November 2014 but he assured her he had not.
On arrival at the stadium, William was greeted by Wales First Minister Carwyn Jones and Stephen Crabb, Secretary of State for Wales.
He then spoke to WRU president Dennis Gethin, chairman Gareth Davies and Martyn Phillips, chief group executive, and Pierre Camou, the president of the French Rugby Federation.
William was interviewed by BBC presenter Sonja McLaughlan and gave his thoughts about the Welsh team under Warren Gatland.
"When the Welsh national anthem goes you know you are home," he said.
"They have done a seriously good job with the World Cup. It was a real shame that South Africa pipped them in the last five minutes.
"I think that in the 6 Nations they have started strong and long may it continue.
"Warren has brought the team together and I expect big things from them."
Following the interview, William spoke to the injured rugby players before arriving at the President's Box in time for the national anthem.
The 11 beneficiaries of the Welsh Rugby Charitable Trust, which was established in 1971, and their guests also attended the game.
Anthony James, 52, had his right leg amputated following an injury and spoke to William about the healing process.
"Fair play to him for remembering me," Mr James said.
"It is the icing on the cake to have him on board with us. He really promotes us. There's so much work done by these trustees for us."
Leif Thobroe, 23, met William for the first time having suffered a spinal injury during a tackle a year ago.
The trust is financially supporting Mr Thobroe through a Masters in Business Administration course at Swansea University.
"I mentioned about the MBA and the Trust," Mr Thobroe said.
"He asked how I was getting on. I've never met him before and I didn't expect him to come and sit next to me.
"That was really nice. He came across as very generous and approachable."
William became vice royal patron of the WRU in February 2007 at the start of that year's RBS 6 Nations Championship.
Last October he launched the Coach Core WRU apprenticeship programme at the National Sport Centre.