Koscielny singled out the North London derby with Tottenham as the key match of the season. The Gunners came back from 2-0 down to thrash their arch-rivals 5-2 and gain momentum in the race for a top-four finish.
He told France Football: "I don't want to have regrets.
"If we have a nightmarish start to the season it's because we deserved it. Frankly I want to come out of this season having matured. The season I went through was tough but full of emotions. Tottenham at our place...
"We had pressure, we were five points behind Chelsea and everyone was saying 'the Champions League is finished, Tottenham will win'.
"But we beat them 5-2 and we put together seven wins. Maybe we didn't dominate all our matches but mentally we had something more.
"At Liverpool for example we always believed and Robin gave us the win at the end of the match."