Thoughts on thinking

What are you thinking when you think about thinking?
What do you feel about thinking?
What do your thoughts make you do (or not do)?
What do you make of the following definitions…

Thought: an idea or opinion produced by thinking, or occurring suddenly in the mind.
Thinking: the process of considering or reasoning about something.
Mental states: a state or frame of mind, a mind-set, or a mental process, such as hoping, believing or fearing.
Cognition: gaining knowledge and understanding; forming memories and putting them to use.

Other words that might be added to these definitions are perceptions, reasoning, problem-solving and decision-making.

It has been suggested that we have up to 70,000 thoughts a day. If you stop to work out the maths on this, that’s around 50 thoughts a minute over a 24-hour period – whether we are awake or sleeping. If this is true, how on earth do we decide which thoughts are useful and which ones are mere brain-chatter?

Also:
Can we learn how to filter out thoughts that are unhelpful to us?
Can we learn how to have fewer thoughts?
Can we change the type of thoughts we have?
Or change the intensity of them?
Can we learn to produce thoughts that are more balanced and in tune with our feelings, our actions and ourselves in general?