A number of years ago the NSF estimated that our brains produce as many as 12,000 to 50,000 thoughts per day depending on how 'deep' a thinker you are (other estimates run as high as 60,000/day).
For those of you who meditate this is unlikely to be a surprise. Meditators are familiar with the 'monkey mind' phenomenon in which the mind is observed as an out-of-control thought generator. As part of my meditation practice I try to remind myself to harness and slow down the 'meme machine' inside my head.
As for regular life, what's disturbing about these 50,000 thoughts per day is that the vast majority of them are pure nonsense. We often dwell in the past or the future, obsessing about mistakes we might have made, battling guilt, planning ahead or worrying. We are constantly drifting into fantasy, fiction and negativity.
Consequently, an absolute minuscule number of our thoughts are actually focused on what is truly important and real: the present moment. The moment is all that is, every was and will be. Everything else is elusive and illusory, particularly as our subjective awareness and feelings are concerned.
Some people have estimated that upwards of 70-80% of our daily thoughts are negative. That's very sad if true. The human mind, it would seem, is wired for neuroticism. A healthy first step to alleviate this problem, therefore, would be to increase one's awareness of these negative and bogus thoughts. This is what's referred to as mindfulness. It's a type of self-reflexivity and enhanced self-awareness that helps Buddhists root themselves in the moment. Once individuals have awareness of these thoughts they can sweep them away from their thoughts like fallen leaves.
You'd be surprised how much control you can have over your thought processes and your ability to control your emotional responses. Even if they number 50,000 a day.