Aulas: Slow Lyon start aged me 20 years
But he said on Sunday the letter was aimed at inspiring them to bigger achievements and make his dreams come true for the rest of the season.
Lyon have recovered from their worst start to a season in 15 years and on Saturday beat Lorient 3-0, extending their unbeaten run in Ligue 1 to 13 matches.
"I sent a long, individual and personal letter to each player to explain to them how I saw the future," Aulas told media.
"I wrote that the first six months of the season may have aged me 20 years, but it did not prevent me from having dreams for this year.
"I related my dreams and told them that to make them come true I needed them."
Lyon, French champions from 2002 to 2008, slumped into the relegation zone after seven matches but now lie just one point shy of leaders Lille.
"I thank the players and the staff for understanding my message and understanding that collective stakes surpassed individual ambitions. We saw a true team (on Saturday) and that was really pleasant to watch."