The actress, 40, (who was recently rumored to be back together with John Mayer) shared a two-hour Italian dinner with Cougar Town actor Josh Hopkins at Madeo in Beverly Hills on Sept. 2.
"She seemed very excited about her date," says a eyewitness. "She and Josh sat at a more private table and they seemed to get along great."
Aniston, who sipped white wine and ordered fish, shared animated conversations with Hopkins, 39. "It was obvious that they don't know each other well, but there was a flirty energy between them and Jen looked very happy," adds the witness.
Reps for both haven't commented on the relationship, but there's no denying the smile on Aniston's face these days.
"Jen has been in the best mood lately," a source tells PEOPLE. "She is trying to do whatever makes her happy, which includes going on fun dates with interesting men."
And the star's optimistic attitude could lead to more fun in the dating world.