Derby County's resolve has been put to the test this season.
Derby lost to Queens Park Rangers in devastating circumstances in last season's playoff final and McClaren thinks his squad have shown great desire to not let that result impact on this campaign.
It would have been easy for everyone around the club to feel sorry for themselves, but their defeat to QPR actually seems to have had the opposite effect and galvanised everyone.
It has led to Derby being one of the Championship's leading title contenders and McClaren feels that it is testament to his squad's resolve.
McClaren: "I think the recovery from the devastation of @wembleystadium has been remarkable from the players. They have been magnificent"— Derby County (@dcfcofficial) March 12, 2015
At the moment the Rams are locked in a promotion battle with five other teams and face a nervy end to the season.
Norwich City, Bournemouth, Watford and Middlesbrough all have ambitions of securing automatic promotion, but Derby will be hoping that they come out on top.
If they were to miss out this campaign, having lead the league standings for so long, it would arguably be even more heartbreaking than last season's playoff final defeat and McClaren will be determined to see this term end in celebration rather than dejection, as a result.