You might want to say:

I'm sure we can count on you doing some more O' training each week, and so you'll soon be in a good position to make the relay team.
 

Or...
Forget the relay team, you're too good of a runner to bother with orienteering. Track starts in two weeks. *wink*
 

well, i'm still young, and also ambitious ;) I'd rather hear the last one, it sounds more positive.
 

Just what is this "relay" you speak of? We in NA only run one a year, and then spend the rest of the time talking about how much fun that one was.
 

Trick question.
Different people are motivated by different things & different ways of saying things. I'd guess more people are motivated by the second statement, but I'm sure there are some people out there who need to hear the first.

I remember before the first WOC '93race, in Harriman, when assistant coach Bob Turbyfill said to me, presumably as a way of psyching me up, "this is the MOST IMPORTANT race of your LIFE!" Okay, I don't respond to that kind of talk (I see it as pressure). I responded, no it's not! He then adjusted: "Well, it's the MOST IMPORTANT race you've ever run in Harriman!" No, I responded, it's not! I ran the North Americans in this park, as well as the Team Trials ... I'm not sure he ever really got what it was I needed him to say (and not say).
Peggy D.