Jonjo O'Neill branded Don't Push It "an unbelievable horse" after confirming the retirement of the 2010 John Smith's Grand National winner.
The 12-year-old gelding famously provided jockey Tony McCoy with his first National success at the 15th attempt, but has signed off from racing after failing to fire on the gallops at his home at Jackdaws Castle, Cheltenham.
O'Neill said: "He's in great form, and he's doing everything grand at home, but he's just not showing us the same old sparkle.
"He's 12 now and we are doing the right thing in retiring him."
Don't Push It returned to Aintree last April and turned in another honourable display when finishing third behind Ballabriggs.
He will spend his retirement at owner JP McManus' Martinstown Stud in County Limerick, having won eight races in a 29-race career which yielded over £750,000 in prize-money.
O'Neill added: "The whole yard, and especially Tony and JP, owe him everything.
"He was also mine and JP's first National winner and obviously means the world to both of us.
"He ran a blinder when he won in 2010, and he also ran a blinder last year when he finished third.
"We thought we had him right again this year after he ran so well over hurdles at Cheltenham, but he's now telling us that enough is enough.
"He's been an unbelievable horse and I'm sure he will be well looked after at JP's - he will have a great retirement.
"He's a smashing horse and will never be forgotten."