Young, who has been on a carefully managed program this season, has been instrumental in steering the Dockers into next week's grand final - where they will meet Hawthorn or Brisbane in pursuit of their maiden premiership.
The 25-year-old starred in the semi-final triumph over Geelong and was a key figure in lifting Fremantle off the canvas in their extraordinary 12-point win over Sydney in Friday's preliminary final.
But it hasn't been smooth sailing for the Victorian left-footer, who had his debut season in 2020 wrecked by a serious ankle injury and has endured a raft of soft tissue injuries in more recent years.
Young also battled concussion from an accidental knock at training earlier this season, which caused him to miss three games mid-year.
"I'm really proud. Some people come into the AFL system and they play from the very start and get a great run at it ... he's been the opposite," Longmuir said after the Dockers' gripping 12.11 (83) to 10.11 (71) win at the SCG.
"He had a serious injury in his first year and it just feels like the last couple of years whenever he's got a decent run at it something interrupts him.
"I've been so proud of his attitude to be able to feel the disappointment of those injuries but then just get back to rehabbing it and getting stronger and better and coming back and performing the way he has."
Young had 23 disposals and one goal against Geelong, and backed up with 28 touches and one goal against Sydney.
His brilliant set shot on the boundary after the three-quarter time siren at the SCG reduced the deficit to 21 points, igniting a run of six unanswered goals as the Dockers surged home.
"I thought he took a really big step forward last week and his physicality was really good all night," Longmuir said.
"He was one of the winners we had in the first half and to get his moment on three-quarter time and finish it gave us a lift."
Young will again be crucial to Fremantle's chances of victory in the grand final when he lines up alongside fellow ball-winners Andrew Brayshaw and Caleb Serong.
Longmuir hailed the Dockers' medical staff for their work with Young and the program that has allowed him to have such an impact in September.
"It hasn't necessarily been about making sure we get him to play 85-90 per cent of game time," Longmuir said.
"It's been to get him to play his role for as long as he can, and we probably think that's around 70-75 per cent.
"But 75 per cent of Hayden Young's way better than zero per cent.
"He's able to influence the game in a lot of different ways and he's starting to really peak at the right time."
13°C