The Germany defender admits that being a substitute like he has been in five of the Gunners' last eight games is not something he wants to get used to.
"Of course I'm playing less, but I'm sticking at it. Maybe I'll get another chance. Things change quickly nowadays.
"You get ups and downs as a footballer and you've just got to remain professional, and I've always been that down the years.
"That's why I've survived for so long in this business. I listen closely to what the coach says and he knows that he can count on me, no matter what happens.
"I want to show him in every training session thadt I'm ready when needed. The team needs every player, whether I'm on the bench now or not - I don't just write it off.
"I always look ahead positively and that is the best way to get over the disappointment of not playing."
The 31-year-old World Cup winner, who has a year left on his Arsenal contract, has played 21 times for the Gunners in the Premier League this season, wearing the captain's armband in all but three of those appearances.
With Arsene Wenger's men having seven games left, Mertesacker has not given up hope of overhauling the pacesetters - but concedes his side can ill afford to drop any more points.
"It's not totally over yet," he told German website sport1.de. "If we win all of our matches, then we've got a good chance.
"We've got to keep focusing on that and that's why we're taking things game by game.
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