Inside Justin Theroux's Life Following Jennifer Aniston Split (Exclusive)

From working on his 'revenge bod' to reconnecting with old friends, the 46-year-old actor has returned to his low-key New York lifestyle following his breakup.

Justin Theroux might still be reeling from his split with Jennifer Aniston, but the former Leftovers star isn't letting that keep him from staying fit.

A source tells ET that the 46-year-old actor has been hard at work on his physique, getting ripped and toned in the wake of the breakup.

"Justin has been hitting the gym hard since the split," says the source. "He's been working out for over an hour every day at Gotham Gym. Boxing is a big part of his workout routine."

Theroux has been spotted numerous times in the past few weeks biking to the upscale gym in Manhattan, and the source says it's because he "loves working out."

"Not only is it great to get ripped, but it's a good way to clear his mind," the source says. "He's always in a better mood after a workout."

The source explains that, while he has "always been in good shape," the Mute actor is now "more committed to a consistent regime" and working toward "his revenge bod."

His dedication to physical fitness isn't the only change Theroux has undergone since the split. He's also returned to his preferred low-key lifestyle.

"When he was with Jen they took cars everywhere, which he hated," the source says, adding that Theroux likes to walk or take his bicycle everywhere in the Big Apple. "Even in the cold weather, Justin's been biking everywhere. He's totally back in his element now."

According to the source, the actor has also started to reconnect with his old group of buddies, instead of staying "holed up in his apartment."

"He's making a point to get out every day and to see friends," says the source. "He's been dining with friends regularly." 

While he's "obviously going through a lot," the source adds that Theroux is "trying to move on, [and] he's dealing with this breakup in a really healthy way."

Theroux and Aniston announced their separation in a statement released to ET on Feb. 15, where they explained that the decision to call it quits "was mutual and lovingly made at the end of last year. We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship." 

In the weeks that followed, Theroux was rumored to have sparked a romantic connection with Canadian artist and photographer Petra Collins, but a source told ET that he "is still heartbroken."

Meanwhile, another source told ET that the actor has been relying on his friends to help him cope with the breakup, and that he recently went on a "guy's trip" to France earlier this month. 

During his visit to the City of Light, Theroux and his pals attended the Louis Vuitton runway show during Paris Fashion Week, and while his friends were hitting the town and looking to flirt, Theroux was friendly rather than flirty, according to the source.

For more on Theroux's split from his wife of two years -- and the major factor that played a role in the problems they faced in their marriage -- watch the video below.

--Reporting by Darla Murray and Adriane Schwartz.