Manners in jogging

What do u do when u meet somebody u know while jogging?

Imagine u are out jogging and in front of u at around 100m u see somebody u know, who is coming towards u, also jogging. How do u react? What do u do?
Salute? He/She is still too far to say something. U cannot shout cause u r running so u cannot do both at the same time.
U smile? For how long?! Will the other one see u?
U stare? Stare like.. an idiot?! For how long?!
The first 50m u can pretend either u didnt see him/her, u got distracted by some ppl walking their dogs or u look down in the idea that u were trying to avoid stepping in some dog sh.. ( she/he will understand!! )
If u decide to wait till u get closer to him/her and then start a sentence what sentence do u choose?!
'Hey. Going home already?' 'Hey, almost finished? I started later today/ Couldnt wake up earlier.' 'Hey. When did u get here?' 'Hey, still doing some laps? How many?'....... Anything u might choose will sound silly. And anyhow u 'force' also the other one to say something, so also his/her training is ruined.
Besides that u might not finish the sentence and need either to slow down, which isn't recommended cause u should keep the same pace otherwise u get tired, or to keep on running but turning a little to finish the sentence.
.. or wave? wave and smile? ..for some seconds when u are at 50m away from the other one and then look straight ahead and continue jogging.. ?!