Many people would sooner die than think; in fact, they do so. Bertrand Russell
Thinking is an essential tool with which to tackle this problem of ignorance. It is, however, only a tool and it must be treated with respect if we are not to injure ourselves. A simple thought, usually second hand, planted in our mind by parent, peer or professor can wreak havoc with our lives. After all, the most vicious terrorist began life as an innocent babe. Once a thought has arisen, it becomes 'my' thought. If I like the look of it, it is very probable that I will become attached to it and it will grow into an opinion. Of course, whether or not we like the look of it depends mostly upon the thoughts that have already wormed their way into our minds and attached themselves to our esteem.
It is worth asking whether you ever actually do anything to bring about a thought. Obviously, people do have 'original' thoughts e.g. people like Einstein are usually credited with having had one or two. Where do these thoughts come from? Do such people generate them; use their exceptional minds to bring them into existence from nothing? Well no, actually. Truly original ideas seem to arise in dreams or dreamlike states when the usual sense of 'I' as the witness is absent.
There are two famous examples. † Kekulé had a vision of a snake biting its own tail and this led to his understanding of the molecular structure of benzene. Coleridge supposedly formulated the complete poem of Kubla Khan in a dream, though this might just have been facilitated by some now-illegal substances. Thoughts such as these 'arise' without the presence of the ego to claim them as its own - pure creativity.
Note that these are quite distinct from the type of thought associated with more traditional 'day dreaming'. We would probably agree that this activity is largely a wasteful one and we often refer to the thoughts that we have as 'idle' to acknowledge this. All other types of thinking that relate to 'me' - what I want, am afraid of, worried about and so on - belong to this 'useless' category; they do not really serve any useful function at all. We may think that we can 'make sense of' the way we feel, 'sort things out' etc. but all that we succeed in doing is becoming more identified with the ideas of which these thoughts consist.
In between these two extremes lie the ordinary, day to day practical thoughts that relate to what we are doing or should be doing. Thus the thought that you have an appointment in an hour's time is probably quite useful. It ought not to be regarded as 'idle', though it is certainly not particularly 'creative'. Practical thoughts are purely functional. They arise from we know not where; we recognise them and their value, take the appropriate action and that's the end of them - no problem!
Creative thoughts wake us up, alert us to new possibilities, solve problems etc. We can take the necessary action and, again, forget about them. Not only are they no problem, they positively enhance our lives. Of course, we cannot do anything to increase their frequency. A special case of this type of thought is one that alerts us to our true nature such as the sudden realisation that we are one with everything around us. This class of thought is rare indeed and, when it occurs, can change our lives completely, causing us actively to search for the 'truth', embark on a spiritual 'path' etc.
Idle thoughts unfortunately often consume a large part of our energy. They seem to be self-sustaining; often triggering related thoughts and spreading the cloud of negativity. 'You will worry yourself to death!' people sometimes say, and this may not be entirely untrue. It all results from the power of identification - the process of ahankara. We latch on to particular ideas and imagine all sorts of related scenarios. Then this breeds 'what if' and 'if only' questions and so on and on… The ego knows no limitations to its egoism! These are really the only type of thoughts to be avoided and the only type that cause problems as such.
* Note that the complete dialogue for this discussion can be read in the Key Issues discourse: Types of Thoughts - Francis Lucille