Maria took two maternity breaks from the WTA Tour and reached the Wimbledon semi-finals in 2022, just one year after the birth of her youngest daughter.
Her message after shocking former Wimbledon champion Elena Rybakina in the quarter-finals was to “never give up”.
She delivered that same motto again on Saturday after making relatively light work of world number eight Keys.
“You always have to keep going. You never can stop, [it] doesn’t matter how it goes,” she said.
“I’ve had my ups and downs but I always keep going.
“I love to play tennis, I love the sport and we live for these special moments – that’s why it’s amazing.”
Keys, one of the in-form players on the WTA Tour, has won three grass-court titles on British soil but was left frustrated by Maria’s slice-heavy style.
Maria immediately put Keys’ huge serve under pressure, finding the breakthrough in the fourth game before securing the opening set in confident style.
Left somewhat stunned and shouting to her box, where husband and coach Bjorn Fratangelo had some words of encouragement, Keys seemed devoid of answers.
But the pair could barely be separated in a tight second set, both saving break points before Maria sent it to a tie-break.
Keys was once again left exasperated as she made a series of unforced errors, with an overcooked forehand gifting Maria four match points.
She saved the first but another error, with Keys missing a swipe at the net, handed Maria a place in her first final of the year.
Maria’s two daughters often sit courtside to watch her matches, with the German saying their presence makes her victory even more special.
“I love to be here with my family, my team. It makes it so special that we live this dream together,” she added.