Aerobic exercises are good to get blood flowing, increase metabolism, and get that O2 goodness to your brain. If you find running boring, taking martial arts classes is a fun alternative.
There are many types of meditation, and different people have different preferences, but to get you started, you might want to find audio tracks (which you can probably find for free) and listen to them with your eyes closed, sitting comfortably, and engaging in deep "stomach-level" breathing. There are lots of websites that have more detailed instructions, so it might be worth looking into. Supposedly meditation helps improve your concentration, memory, focus, and reduces stress, which is all nice to have when studying for the beast that is MCAT.
Playing games like chess or go on a serious level may help too, since the level of focus is quite similar, though I wouldn't pick it up for the sake of Verbal.
Or it may just be something else in your mind that's bugging you, preventing you from being able to fully focus. Then you'd have to take steps to address whatever this may be.
Some people find taking a day off to the beach or park helps, if only because it reminds them that everything is alright and life is good.