Emma Hayes said she is "absolutely leaving at the right time" as her 12-year tenure in charge of Chelsea came to an end.
The 47-year-old bowed out with her fifth successive Women's Super League title and her seventh overall.
An emphatic 6-0 win over Manchester United at Old Trafford means Hayes departs with 14 major honours, including five FA Cups and two League Cups.
In a thrilling finale to the WSL season, Chelsea pipped Manchester United to the title on goal difference.
"It has taken its toll," Hayes said. "I categorically cannot carry on. I don't have another drop to give it.
"There is so much of the job, dealing with people, and when you deal with people I have such high standards for myself that maintaining that has become impossible.
"I can't keep up with the demands from players on a daily basis, in terms of their emotional needs, in terms of everything, and I've found that to be gruelling this year.
"I hope that the club really supports the new manager to get player care and a little bit more performance psychology.
"I really believe in the wellbeing, even though I can't take care of it in the same way.
"I've made my suggestions to the sporting directors and I know they'll take it on. It was lovely to have them here today."
Since the announcement in November that Hayes will take charge of the USA women's team, she has been keen to talk about her players and their games rather than the end of her chapter at Chelsea.
But in her final post-match news conference on Sunday, Hayes reflected on her contribution to the game.
"I just wanted to create role models that I never had," she said. "I just wanted to create a profession that wasn't possible.
"I get asked that question all the time: 'Would you have been a professional footballer?' How could I have even dreamed about that at 10 when there was no visibility on television?
"We've all been told 'no'. We've all been told it can't be done. We've all been told the boys come first. We've all been told it's a men's game.
"For this final game at Old Trafford, then there's a sell-out at Wembley, there's England winning the Euros, Arsenal selling stadium out after stadium, game after game.
"Women's football will explode. It's already exploded, but it's going to really explode in the next few years. And that was all that I wanted."