One of the more subtle, yet profound, practices i have maintained for the past 10 years is a simple one. Its something that i recommend to others when they ask me for advice on practices to incorporate their training into their daily lives.
Buy a small bell and hang it from the ceiling by a string. A good place is about 6 inches above the shower head. As you shower, you may notice a thought come to mind. As you notice this thought give the bell a ring.
There is no competition intended, no striving to 'not think', but just a simple noticing.