Sherlock waits, straining to listen. He can hear cupboards opening and closing and the coffee pot beginning to boil. He was prepared to wait as long as it took to catch him, and he knows how long John lingers in the kitchen with his coffee so he knows about how long he'll be there before he comes out here to find the paper. Since he's not making a full breakfast, he won't bring it back to the kitchen to read, but probably settle down in his chair with it. That means, unfortunately, that he'll probably come out carrying his mug, but some casualties are bound to happen during these training exercises. He's only partly suggested it to prove his point, that John thrills at the absurdly dangerous. The rest is all sincere, the idea that it will do them both good. Hone their skills and their senses.

As soon as John emerges from the kitchen to the sitting room, Sherlock is in motion, bare feet hardly making a sound on the hardwood floor, and what sound is made hardly matters because he's on him so fast and so without warning that there's hardly the time to realize what's going on. All at once, Sherlock collides with the doctor head on and grabs for him, taking full advantage of having surprise on his side and gaining the upper hand for the moment. He's thrown an arm around him to pin John's arms and together they're toppling to the ground in a relatively controlled motion, all things considered. But this isn't over until John concedes defeat, or until Sherlock effectively pins him to the floor.