Williams avoided a major upset on Tuesday as the former world number one battled back to beat unseeded Camila Giorgi 3-6, 6-3, 6-4 in a Centre Court thriller.
The 36-year-old's quarter-final escape act set up a last four showdown with German 13th seed Julia Goerges on Thursday.
Serena hasn't won a Grand Slam since the birth of daughter Olympia in September and her last trophy came at the 2017 Australian Open.
"You're only as good as your last win. It's been a while since I've won a championship," Williams said.
But the 23-time major winner is heavily favoured to end her wait this week, fuelled by the thought of suffering the painful sting left by her rare defeats.
"I hate losing. I mean, that's no secret. But I feel like every time I lose, I get better," she said.
"It's important for me to have the losses. Just the fewer the better for me!"
Williams is playing only her fourth tournament since becoming a mother for the first time.
Having shaken off the rust following her lengthy lay-off after the complications with Olympia's birth, Serena is on the verge of a 10th Wimbledon final appearance and 30th in all four Grand Slams.
"Everything right now is a little bit of a surprise, to be here, to be in the semi-finals," she said.
"I always say I plan on it. But when it actually happens, it still is, like, Wow, this is really happening."
With Olympia's arrival and her marriage to husband Alexis both taking place since Serena was last at Wimbledon, this year's campaign has a unique feel.
"It's different now obviously because I have the baby. Being a mom is totally different," she said.
"I just want to be more of that role model for my daughter, for lots of people out there that just want to be inspired.
"Here is some good news. Right now there's so much bad news in the world. We just need a good story."
Having won the title in the previous two years she played Wimbledon in 2015 and 2016, Williams, who missed last year's tournament due to her pregnancy, has extended her winning streak at the All England Club to 19 matches.
In contrast, Goerges is in the Wimbledon semi-finals for the first time.
The 29-year-old had suffered five successive opening round defeats at the All England Club before this year.
It also took her until her 42nd Grand Slam appearance to finally get through to the last four at a major.
Yet Goerges insists she can cause an massive upset against Williams.
"It is a great opportunity to play Serena here where she has won so many times and is a great champion. I think everyone here has a great chance so you have to take it," Goerges said.
Angelique Kerber, the German 11th seed, faces former French Open champion Jelena Ostapenko in the other semi-final.
Ostapenko struggled with the pressure of defending her maiden Grand Slam title, losing in the first round of the recent French Open.
But that lifted a weight off her shoulders at the All England Club, where she has become the first Latvian to make a Wimbledon semi-final.
The 21-year-old is the only female player yet to drop a set in this year's tournament.
"At the French Open a couple weeks ago I had so much pressure. It's now all gone," Ostapenko said.
"I'm just enjoying the moment. It's so much fun."
However, Kerber, beaten by Serena in the 2016 Wimbledon final, doesn't believe Ostapenko will be able to play completely free of anxiety with the title match within touching distance.
Kerber, the 2016 Australian and US Open champion, said: "I mean, the pressure is not always on my side. She (Ostapenko) won a Grand Slam, as well."