Over the past couple months my son’s become increasingly fascinated with comparison. He’s beginning to understand comparative words (e.g. older, younger, shorter, taller, bigger, smaller, etc.) and is constantly looking for ways to use them.

For instance, he’ll ask how old someone is, and as soon as he gets an answer he’ll begin to verbally figure out how that age relates to other people he knows. He’ll do the same with people’s heights. It’s not uncommon to overhear him talking about how Joey is older than Jimmy, but how Jimmy is taller than Joey. And how both of them are younger than Jill.

Learning how to compare is part of growing up, and can be a valuable skill to have. When faced with multiple options, knowing how to properly compare them can help you make better decisions, and may even save you money or pain down the road.

But there are other times where comparing does you little good—and may even cause some harm. You can be tempted to compare your life with those you see online, forgetting that you have no idea what’s really going on behind the scenes. Or you can allow your contentment in life to be altered by comparing what you have with those around you. What was once a perfectly nice car or house or phone suddenly isn’t good enough because of what others have.

Or you can get caught up in the comparison of things that are beyond your control. You can’t control your physical features, or your family-of-origin, or certain opportunities you may (or may not) have had in life. And yet, if you’re not careful, you can wind up comparing yourself to others in these areas, instead of simply focusing on running your own race.

Knowing how to compare is a valuable skill to have in life. But knowing when—and when not—to compare can be just as important.