Justin Theroux uses his love of boxing to stay in shape.

The 46-year-old actor - who is best known for his roles in 'The Girl on the Train', 'Zoolander' and 'American Psycho' - has opened up about his workout regime and admits he loves sparring in his spare time and says the sweet science keeps him fit and healthy, although he has to stop himself from getting too competitive between the ropes.

In an interview with Men's Health magazine he spoke about a time in the ring with a female trainer saying: ''I hate getting hit. And she's so fast, a better boxer than me, by far. It's so frustrating. A couple times she really rang my bell. And I was a combination of hurt-slash-p***ed.

''Am I gonna cry or knock her head off? But I couldn't touch her. Too quick. But I see that a lot in sparring. People get p***ed, get emotional, and that's kind of the point of sparring: Keep breathing, remain loose, not tense.''

Justin - who recently split from his wife of three years Jennifer Aniston - also uses his time whilst his not filming to exercise for up to an hour five days a week, working on his abs, doing circuits or dead lifting.

The Hollywood hunk also spilled on his attitude to life, insisting he likes to make spontaneous decisions.

He shared: ''I happened to be driving by a skydiving school once and decided to go skydiving. A split-second decision. It wasn't anything I planned. I always wanted to ride a motorcycle across Europe. I've done that three times now.''