Lazio are 10th in Serie A, four points adrift of fifth-placed Inter with two games remaining and still a chance to qualify for the Europa League.
Reja returned to the Rome-based club for a second spell after replacing Vladimir Petkovic, who was relieved of his duties in January having agreed to take over as coach of Switzerland at the conclusion of the FIFA World Cup.
The 68-year-old tactician has guided Lazio to 10 wins, six losses and seven draws since returning to the Stadio Olimpico and believes he is not getting the recognition he deserves.
"I can say simply and honestly, we have gained 33 points under me," Reja told reporters ahead of Saturday's trip to Inter.
"If I had been here for the other half of the season we would have got Europa League football, definitely.
"I am sorry that we are not getting recognition for what we are doing. The circumstances we are playing under are not easy but yet we are still getting great results."
Reja added: "Our recent results are a shame, our destiny was in our hands before that. Against Torino and Verona we didn't manage to do what we set out to do.
"We have still managed to get a lot of points, but here you are criticised all the time.
"We still have a small chance of Europe and we want to go for it despite all the difficulties that surround us."
Lazio have won their past four games against Inter, with their last defeat a 2-1 loss back in January 2012.
