Hanging out with friends at the post-Saturday Night Live bash in the early morning hours of Nov. 16, an upbeat Jennifer Aniston was the life of the party. “Jennifer looked great—she was all smiles and kept jumping up from the table to greet people,” says an observer at New York City’s Dos Caminos Park restaurant. “She seemed relaxed, enjoying talking to her girlfriends.”

Reenergized, refocused and refreshingly candid, Aniston—who turns 40 in February—has been making the most of a whirlwind autumn: promoting her Christmas Day film Marley & Me, opening up in interviews and rekindling her romance with musician John Mayer. After breaking off their relationship in August, the pair are giving it another go—and this time, they are speaking out about their mutual affection. “He is a wonderful guy,” she told Vogue‘s December issue. For his part, Mayer, 31, tells PEOPLE of Aniston, “I have her back and she has my back. That girl just knows me.”

Aniston also seems to be in a good place with her ex Brad Pitt, telling Vogue, “I’m proud of him! I think he’s really done some amazing things.” (As for Angelina Jolie, she called the actress’s 2007 revelations about her budding feelings for Pitt “really uncool.”) For now, though, Aniston is enjoying the present—in particular, her “unbelievably lucky” love life. “I feel good,” she says. “I’m right where I’m supposed to be.”