The arrival of Erik ten Hag at Old Trafford in the summer saw the Portugal veteran's game time restricted and, as his unhappiness grew so did his frustration, which led to an unauthorised and explosive television interview with Piers Morgan in which he criticised the club.
That ultimately led to his contract being terminated by mutual consent and him joining Saudi Arabian side Al-Nassr.
"I have no problem saying I had a bad phase of my career, but there's no time for regrets," he told a press conference ahead of Portugal's Euro 2024 qualifier against Liechtenstein.
"Life goes on and, doing well or not, it was part of my growth. When we are at the top of the mountain, we often cannot see what is below.
"Now, I'm more prepared and learning that was important, because I had never been through this, like in the last few months. Now I'm a better man."
There had been speculation the 38-year-old would bring his international career to an end after the World Cup in Qatar but the arrival of Roberto Martinez as head coach has given him optimism for the future.
"It's a different chapter for all of us. The energies are good, positive, that's the most important thing," he added.
"There's fresh air now, different ideas and mentality."