Kingston was sidelined under Csaba Laszlo after the former Hearts manager question the midfielder's commitment.
Kingston told the Hearts website: "I am so, so happy about the new manager. He is like a father to me now."
Jefferies has given the Ghana international a clean slate and has urged him to take advantage of this fresh opportunity to get his career at Hearts back on track now he is free of injury.
No-one is perfect and everyone has problems in their career but I just want to get back playing.
"It has been a long time since I last played and I was happy to see myself back at Tynecastle," said Kingston. "It was great to be back.
"No-one is perfect and everyone has problems in their career but I just want to get back playing. The first time I met him, I was so happy with the way he spoke to me.
"He is an experienced manager and, the way he spoke, I knew he has something to give this club.
"Everybody is happy in training and the morale in the dressing room has changed. It is a very good thing he is here."
Before Jefferies arrived at Tynecastle Kingston had made only three starts and two substitute appearances this season.
Kingston added: "It is important that I don't let him down as he has supported me so well. I know I have to work hard in training and in games.
"It is not about me talking, I have to stay quiet and deliver on the pitch, give 100%."
Source: BBC Sport