There are things we can influence and usually a broader array of things we are concerned about though can't influence. It's important to know the different otherwise we waste our energies trying to change things we have no influence over. There is a also a video
for this insight which is a component of the Effective Problem Solving Course
How much time do we spend thinking about things that are relevant? How relevant are the things we spend time thinking about? How would you tell the difference? And just what does the question really mean?
Out of the endless network of relationships there are a few of them that you actually have some amount of influence over. These are what are really relevant and you'll get a sense of why in a moment.
Your area of concern is typically far more encompassing than your area of influence. And while you may concern yourself about things in this area there's essentially nothing you can do about them. The only extent to which they have any relevance is where they have an affect on that which is within your area of influence, and then you just have to figure out how to deal with them.
It has been shown that if you focus on what's within your area of influence it tends to expand. And if you focus on that which is within your area of concern your area of influence shrinks. Covey talked about this in "The 7 Habits of Highly Effective People."
If you really want to address that which is within your area of concern then you will need to find collaborators who have influence in the areas you don't. Among you you will have a chance of addressing the situation being considered.