The 22-time grand slam champion lost her world No. 1 ranking to Angelique Kerber this month when she was dumped out of the US Open at the semifinal stage.
Williams has struggled with injury over the past year, with shoulder and knee problems increasing her frustration throughout the season.
And the American -- who turns 35 next week -- is refusing to put a date on a comeback, instead focusing on making sure she's close to full fitness before making a return.
"I'm tired of playing tournaments unhealthy and taking losses that I would never lose," Williams told CNN at the unveiling of her French coach Patrick Mouratoglou's new tennis academy near Nice.
"I definitely want to make sure I'm healthy and playing at my best or at least 80% healthy or 70% healthy -- that way I can be able to play at a higher level."
The knee injury appeared to play a significant part in Williams' shock defeat by Karolina Pliskova
in the last four at Flushing Meadows.
While she refused to blame the injury for the loss, the result meant she managed to land just one grand slam title compared to the three she won a year earlier.
Williams has three tournaments scheduled for the rest of 2016
: Two in China, then the season-ending WTA Championships in Singapore starting October 24. She missed the tour's Asian swing last year due to injuries.
Mouratoglou offered a frank assessment of the problems his player -- who won Wimbledon to match Steffi Graf's slam tally
after losing finals at the Australian
and French Opens
-- had faced over the past season.
"We have to be honest -- it has been a bad season for her," he told CNN. "She's been injured a lot, which makes it worse because she couldn't play much.
"She played only eight tournaments, which is really, really, not much. For Serena, any result that is not a title is a bad result -- so a final of a grand slam is a bad result for her. We can't be satisfied with one grand slam final and two finals lost.
"It's a bad year, there are many explanations but we have to learn and be better next year and that is definitely the goal. This is not satisfying at all."
While Mouratoglou was happy to discuss Williams' travails of the past 12 months, the world No. 2 was altogether more terse.
Asked about her reflections over the past season, Williams said: "Yeah I'm not talking about that so ..."
And questioned about regaining her world No. 1 spot from Kerber,
she added: "I'm not talking about my career. If you want to talk about other things that's okay ..."
Williams was more forthcoming when asked about her fashion line which enjoyed a showing at New York Fashion Week.
She unveiled the Serena Williams Signature Statement fall collection, presented by HSN, last week, and says the business commitment has little effect on her tennis. And with a day's rest between matches at the US Open, Williams was able to keep one eye on her fashion line.
"It's easy for me because when I'm on the court I'm really, really focused," she added. "I'm playing every other day so I have plenty of time just to go through small things. I have a wonderful team that I work with and they really do a lot of the work.
"I think they get a little bit intimidated when I come in and change everything and say, 'It has to be this way.' So that's also really cool."
So what's more difficult -- playing at the US Open or planning a fashion show?
"I don't know," she said. "I think they are pretty equal. Fashion is probably a little easier I guess but at least in a grand slam I can control what happens.
"In a fashion show I can't necessary control what people may think of the garments you put so much work into."