The Royals were only denied a place in the Premier League by a penalty shootout defeat to Huddersfield Town at Wembley last May, but their 2017-18 Championship campaign got off to a poor start as Conor Washington's brace condemned them to defeat.
Reading also saw Tiago Ilori sent off at Loftus Road, but Stam believes that his side were simply below par rather than suffering any lasting effects from their playoff heartbreak.
"The players need to be up for it again and they are. The playoffs is an easy excuse. It needs to be an inspiration for the players - and it is," he told reporters.
"You have to want to be in that position again and we do. To do well you have to work hard and have some pain at certain times. We just didn't play well. We knew QPR were going to play a certain way to stop us getting opportunities and they did that very well.
"The sending-off was obviously a turning point but at 1-0 we had chances and didn't take them. We were not good enough and if you don't do what you need to and bring a certain level of aggressiveness you are not going to beat teams."
Reading's next match sees them host Gillingham in the League Cup on Tuesday.