The US Open starts on Monday and Murray will open with a first-round match against Nick Kyrgios.
Murray got married earlier this year and his form since then has picked up as he won the Madrid Open title. Speaking ahead of the final Grand Slam of the year, Judy insists it has made him more relaxed on court.
The Scot won his first Grand Slam at Flushing Meadows and he will return to Queens in New York City to try and win his third.
"He's relaxed and I think everything that has happened means he has an extra sense of responsibility now that he's a married man and a dad to be.
She said: "He's had a really good year so far.
"The results since he got married certainly would prove it's working for him. He's been moving very well and when he moves well he plays well.
"It's something Amelie [Mauresmo] has helped bring back into his game - changes of pace, slice, drop-shots, coming forward more.
"I'm enjoying watching him playing that kind of tennis again. The key is he's learning how to become more aggressive at the right time."