There’s a lot to be said for keeping things simple, especially when it comes to a workout routine . Rushing out to buy the latest “essential” fitness gadget or sign up for every new class can be exhausting—and not in a good way. For Men’s Journal January cover star Justin Theroux, staying in shape means sticking to tried-and-true methods: lifting, boxing , biking , and walking. Paul Rudd and Justin Theroux Talk About Friendship and Making Netflix's 'Mute' “It’s lifting weights, heavy things, a couple times a week,” he told Men’s Journal behind the scenes at our January cover shoot. When he’s not lifting, he’s likely throwing punches with a boxing routine, which, he adds, is good for keeping his reflexes and motor skills sharp. He’ll fit in both types of workouts during a typical week. Can You Handle Justin Theroux's Hardcore Workout? But fitness, as we all know, doesn’t have to be confined to a gym—nor should it be. In addition to lifting and boxing, he also like...