Great advice for negative things. Pay them no attention, after you've processed them (don't ignore them though!).

For positive things, for future hope and dreams, one has to be careful. We know that visualizing a positive outcome can be counter-productive...

Those who daydream about the perfect fitness routine don't go to the gym.

Those who daydream about building anything are less likely to take the step necessary to actually build it.

It's as though strong visualization of a positive outcome becomes a satiating reward in itself. Without any changes to reality, we become attached to the mere idea of possible future. Just as those dwelling on the past are dissociating from reality, those hoping for the future are willfully disengaging engaging with primary reality.

All that is to say, it IS all about attention. So pay attention to the present.