The 35-year-old completed a decade at Goodison Park this summer and marked the achievement by signing a contract extension that ties him to the club until August 2019.
The former England international was once a first-team regular for the Merseysiders but has slipped down the pecking order under Ronald Koeman, playing in just half of Everton's fixtures this season.
Jagielka says it still hurts when he is not involved for the club but he is trying to adjust to his new role.
“There’s not a single little bit of me that is glad when I’m not playing but I understand with my age, getting more people in and it being a squad game, your role has to change slightly," he told the Liverpool Echo.
“I’m still trying to keep myself as fit as possible and give the manager as much of a headache as I can for every game.
“Playing every game is not guaranteed so it’s up to me to do the best I can and see where it takes me.”
Jagielka says he had options to leave Everton in the 2016 summer transfer window and in January this year, but says he did not want to step down to a smaller club at this late stage of his career.
He added: “There were options to try and leave and go and play regular football, either in the same league at a lesser team, even in a different league, but I’m at a great club here and I still want to fight for my place."