The phrase "catching up" (which I use routinely) typically is referring a timeline.  Something along a horizontal axis.  Time has marched on and I need to "catch up" to the current point and learn what has been going on with you.  

It struck me recently that this same phrase could have a different meaning.  To catch something is to capture an item in motion or to observe something that might be been in secret and "up" is a reference to altitude (a vertical axis). So, to catch up with something or someone would be to see the best and them and to stop and acknowledge it.  To catch someone in the act of doing their best, of feeling their best, or being their best. 

And I bet if we sought to catch up in this way, we'd find a lot more examples of excellence and achievement around us!