The weights never leave you. It infests you. More than running, swimming, bike riding. If you quit for some time and see a dude walking by who is "built" you remember your old self. If you are watching a football game and you see a player throw up a double biceps after a play, you remember. When you walk by the weight benches at a dept store, you remember.
When you do push ups, and get that pump in your triceps and chest, you remember. When you look down at that spare tire, you remember that "6 pack". Hell, when you are changing a tire, you remember how light it used be back when you were lifting, and how it didn't take that much torque to get the wheel off.
Weight training is not so much the action, but the lifestyle and the physical growth that you can see with your own eyes. Damn near anybody can run, or ride a bike, and this is not taking away from those sports, but not too many people have the discipline to take years of developing themselves, much like a martial arts.
The true key to balance is utilizing weight training with other forms of athletics...