Atletico Madrid remained on top of the La Liga, despite Barcelona and Real Madrid victories, thanks to a hard-fought 1-0 win over Villareal.
Raul Garcia's 14th-minute goal settled the contest, but the hosts had to withstand heavy pressure in the closing stages to see out the match.
"We've been making a huge effort, incredibly so, I can't find the words to keep congratulating the players' effort," Simeone said on the club website.
"It was a complicated match and we achieved an important victory.
"At the end we were tired, which is normal. The strength and energy we had in previous occasions were not there, but the team was level-headed, and that made up for the lack of energy."
Atletico are now six games from the title, with a trip to Barcelona coming on the final day of the season, and the Argentinian admitted none of them would be straightforward for his side.
"I can't imagine an easy game seeing what's ahead of us," Simeone said. "Getafe and Elche, Malaga with their needs, Valencia and Levante. And you know about the last one."
Real Madrid boss Carlo Ancelotti vowed his club would fight until the bitter end for the Primera Division title after keeping up the heat on the top two with a 4-0 thrashing of Real Sociedad.
Madrid remained two points adrift of Barcelona and three behind leaders Atletico Madrid with a convincing win, crowned by two late goals.
"We played very well, intelligently," Ancelotti said. "I'm very proud to manage this team. I have players who like to fight and we're going to fight until the last match."
Barcelona boss Gerardo Martino insisted he was interested only in the win, not the performance, as his side kept up their title charge with an unconvincing 3-1 victory over Real Betis.
Martino admitted it was a match the Catalans just needed to get out of the way, with the second leg of their Champions League quarter-final against Atletico Madrid looming on Wednesday.
Two goals from Lionel Messi and an own goal from Jordi Figueras secured the win, with Ruben Castro on target for the visitors, but Barca never looked totally comfortable.
"In a sense I was expecting the match to not play out like our previous ones. For once, I'm going to focus 100 per cent on the result, not how we played," Martino said on the club website.
"I don't want to make excuses. The feeling that I have is that, in between the game (against Atletico) this past Tuesday and the one next Wednesday, this match against Betis snuck up on us. We needed to win in order to continue putting pressure on the leaders."