England and Saracens star Maro Itoje insists he is still mentally fresh after an arduous Six Nations campaign.
Former head coach Sir Clive Woodward said Itoje looked "out on his feet" as England lost three games and finished a lowly fifth in the championship.
But the 23-year-old returned to club duties with a man-of-the-match display for Saracens in their 24-11 Premiership win over Harlequins on Saturday.
"I think the mind is a powerful thing," Itoje told BBC Radio 5 live.
"It was good to be back and I'm feeling good."
Itoje's heavy workload for his club, England and the British and Irish Lions over the past few seasons has led to suggestions the flanker is mentally and physically fatigued.
But his impressive individual performance at London Stadium was capped by an individual try, with Itoje pretending to be asleep in celebration.
However he denied being influenced by the external criticism of his form and fitness.
"I don't take any motivation from outside sources," Itoje said. "All my motivation comes from my team-mates, my coaches, myself and my family. That's who I pay attention to. Luckily I've got youth on my side and all is well really."
Saracens director of rugby Mark McCall said Itoje was "full of energy" against Quins, but stressed the player would be carefully monitored for the rest of the season.
"He's had a quiet week with us in terms of training," McCall said.
"I think it's very easy to freshen players up to be honest, but Maro is someone we are going to keep an eye on over the next four weeks. But it gives him a lot of confidence going into the big game [Saracens' European Cup quarter-final against Leinster] next week."
And McCall said he was happy to take feedback from the England players before deciding to select them against Quins.
"If any of them had said to me they really needed a break then we wouldn't have [selected them]. But they were all very keen to be with the team before next weekend."