Exercising your creative mind is as important as exercising your body. Nothing else is as handy as carrying a sketchbook and of cause with a pencil. You can slip it in your bag or back pocket and sketch anytime and anywhere.
Drawing helps you to rediscover the surrounding around you and you will start finding that you will see familiar things in new lights. It is like keeping a visual diary, you can look back many versions of your drawing which can bring back images of your emotions.
So start drawing something every day!