Goalscorer Gylfi Sigurdsson says Everton's collective disappointment at their first-half showing against Chelsea gave rise to their extra intensity after the break.
Sigurdsson struck his 12th Premier League goal of the season after his own penalty had been saved by goalkeeper Kepa Arrizabalaga on 72 minutes to complete a 2-0 win for the Blues.
Richarlison had earlier reached a dozen top-flight goals himself, reacting instinctively to nod in after Dominic Calvert-Lewin's initial header had been repelled by Kepa in a high-energy opening to the second period.
That followed a first half in which Chelsea had enjoyed the lion's share of the chances, hit the post through Eden Hazard and seen a Pedro effort ruled out by the offside flag.
"[At half-time] we said we needed to be completely different in the second half," said Sigurdsson.
"It was poor from us in the first half, we were second to everything and it was a lot different after the break.
"It was much better, more attacking, there was more movement and we won a lot more second balls in the second half, and I thought that was important for us.
"We defended well even though Chelsea were on top in the first half, and we were still in the game. We always thought we were going to create chances and we took them when they came in the second half."
Before the break, centre-back pairing Michael Keane and Yerry Mina, starting a game for the first time since December 29, marshalled Chelsea forward Gonzalo Higuain, while Jordan Pickford made a number of crucial saves, notably plunging to his left to thwart dangerman Eden Hazard in the opening minutes.
Sigurdsson praised the way the Blues' rearguard kept them in the contest leading up to the interval - and after it helped ensure a victory that moves Everton to within four points of seventh-placed Wolverhampton Wanderers.
The Icelander also spoke of his joy at coolly slotting home the second goal after seeing his penalty well stopped by Arrizabalaga.
"It's probably better to score from open play than from the penalties if I'm going to try to be positive but I managed to put it away after he made a save and I thought the defensive side of the game from us was very good in the second half," he said.
"We dealt with [Chelsea] and obviously they're very good going forward, with a lot of quality players.
"It was nice to get a clean sheet because that was one of the things we talked about before the game."