The former world No.3 and two-time grand slam finalist will spearhead Greece's United Cup charge in Perth, beginning against Naomi Osaka's Japan on Friday night.
He lost in the first round at last year's Australian Open, where he was a finalist in 2023, and retired mid-match at Wimbledon due to chronic back pain.
"My biggest concern has been, can I actually finish a match?," Tsitsipas, now ranked 36 in the world, told reporters on Thursday.
"That was what was going through my mind the last six-to-eight months.
"I was constantly thinking, if I win a match, will I be able to come back the next day and play another match without pain?
"There were phases during the year where I was asking myself, 'Why am I doing this, and why am I putting myself through so much pain?'.
"I got really scared after my US Open loss with my back, because I just couldn't walk for two days.
"When things like that happen, you start reconsidering the future of your career.
"I'm just hoping 2026 doesn't bring any of that."
He's arrived in Australia pain-free and "hoping it stays that way" to get back to his best with father Apostolos back in his corner after a brief union with Goran Ivanisevic last year.
Tsitsipas acknowledged their combustible relationship caused a counterproductive "friction" in the past and has added another voice as a "filter" to avoid a repeat in their reunion.
"So far we've been managing it better. It did get a little bit misunderstood in the past. I did some silly things that I shouldn't have done actually," he said, smiling.
"It's a Greek tragedy, one of those type of situations.
"Working with family is never easy, and it's one of those challenging things that you have to tackle daily to separate the father role from the coaching role.
"It's really important to stay honest and to stay true to yourself.
"The biggest issue in the past with me and my father is obviously we're two strong personalities, and we want to express our opinions. Sometimes they don't really co-align.
"It's important to know where you put an end and a stop to it and accept and talk through certain things that might cause friction."
Spain and Argentina will open the action in Perth on Friday morning before Sydney's fixtures commence on Saturday.
The mixed event will feature five of the world's top 10 men and four of the world's top 10 women, including Alex de Minaur, Coco Gauff, Taylor Fritz, Iga Swiatek, Alexander Zverev, Jasmine Paolini, Felix Auger-Aliassime and Jack Draper.
Australia's campaign begins in Sydney against Norway on Saturday night.
