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.
