It seems when we set out on an endeavour or project - we often focus too much on the big goal of completing the project - we dream of the glory of the achievement and 'cash in' the feelings associated with the positive result before it has occurred. It appears this can seriously hinder the finalisation of the project, however, and is therefore dangerous.
When we consider doing some work on a project; whether it's improving our health, or completing a report, if we come up against some obstacle that daunts us, it seems we can often give up temporarily, or even completely, because it challenges the imagined realisation of the dream which has been giving us so much pleasure in our lives.
If we stop dreaming, however, and recognise that major achievements are reached via many small steps, then we can just choose one small step forward to work on at a time - and recognise that step for it's worth outside of the big dream.
It appears that if our dreams are worthwhile and honourable enough, any small steps taken in the direction of realising them will provide us with more immediate benefits in our lives and will therefore become a substitute for dreaming in order to feel happy.