The Real Madrid boss admits that the strain of coaching the Spanish giants is "wearing him out".
Zidane - who previously stepped down as Madrid manager in 2018 before returning 10 months later - hinted that it won't be "20 years" before he leaves the Bernabeu once again.
He said: "I won't coach for 20 years. I'll retire before that.
"I'm an unusual coach, anything could happen. I'm not planning anything. It's the day-to-day that excites me. For how long, I don't know.
"In my head I've always been a player. I played for 18 or 19 years, and after that when people asked me if I'd be a coach, I said no.
"Then I decided to become one. This really wears you out. It won't be 20 years, that's for sure."
Zidane's side opened up a two-point lead over Barcelona at the top of the La Liga table after beating Espanyol 1-0 on Sunday (28.06.20).
Casemiro scored as Real maintained their perfect record since La Liga's resumption following the coronavirus pandemic and Zidane feels that the title battle will go down to the wire.
He told Movistar: "This will be decided at the end of the season.
"I always think about the league I won as a coach in 2017. We won it in the last game (a 2-0 win at Malaga). The same thing will happen here.
"We're happy with five wins in a row but it doesn't change anything, we've got six finals left."