"Once in a while that feeling would go away when I was home with the (three) kids. A couple times it would come back. It got stronger and stronger."
There will be no easing back into the game, as she will face Garbine Muguruza - last month's Australian Open losing finalist - in her first match in seven years, on Monday.
"I talked to my husband. He was like, 'stop worrying about why and ask yourself why not.' she continued.
"He made a very good point. I was like, 'There is no 'why not'. Why wouldn't I do it?"
Clijsters is able to take part as a wildcard after years out of the game, and gave more details on her progress since deciding to mount a comeback: "I've enjoyed the challenge since the day I've decided to go for it. It's been with ups and downs.
"Being 36 years old, you know that's how it's been for your whole career. It's how you mentally stay through it, how strong you stay through those kind of situations."
"It's been an interesting but very challenging process that I'm really enjoying."