Try or try not. There is no do.
One of my pet peeves is the undeserved malignment of "try." Motivational speakers, church teachers, and armchair psychologists are the worst offenders. They say that "try" is negative and evil, and invariably they quote Yoda (or implicate the quote in paraphrase if it wouldn't be appropriate to quote a little green man directly): "Do or do not. There is no try."
Now, Yoda had a really good point. Yoda was wise. Yoda would roll over in his grave at the way people misrepresent his words, if he wasn't just a muppet. Sometimes we will say to ourselves or others, "I'll try," with the same defeatist attitude that Luke had, or let ourselves succomb to fear or whatever other thing that might keep us from achieving. This is what Yoda spoke out against. This is what the maligners of try should be addressing. But they get fixated on this word which has a real true and valuable meaning that should not be ignored, and declare that it is negative, when it isn't.
Usually I just cringe and bear it, until someone comes along and breaks the camel's back by doing that ridiculous rock demonstration. They will ask someone in the audience to "try to pick up this rock". This is entrapment. Even if the volunteer has already seen the demonstration (he has), he's stuck. If he doesn't pick up the rock he is uncooperative. If he calls the bluff then he looks like a smartypants and risks ruining the effect for the 0.01% of the others that haven't seen the demo yet. If you're one of the 0.01%, the trick is that the volunteer gets chastised for actually picking up the rock instead of "trying" to do so. The implication is that you can't "try" to do something, you can only do it. This is absurdly obvious when it comes to picking up pebbles and so everyone goes home believing that "try" doesn't exist.
At this point I like to give a counterexample along the same lines. I say, if there's no such thing as try then when I tell you "win a race" and you fail to do it, it is because you didn't decide to win. You didn't want it bad enough. Of course, there are people that believe this fairy tale version of sports too, but that's another post. When there are external factors that you can't fully account for, the best you can do is try. You can try to win the race. You can try really really hard. If you do try, and you happen to be the fastest, then you win the race. If you don't try, you don't win the race. If you don't believe in try, then either your head explodes when you don't win the race you set out to win, or you never run the race in the first place because you haven't got any assurance that you will win.
Of course, the very thing you are being motivated to do is always this sort of thing where the best you can do is try. Whether it's being a good little boy or girl for the rest of your life or being a totally pointy manager, the variables are too many for you to "do or do not." The best you can do is try, and the way you try is by defining the actions you have control over and doing them. The individual actions are done, not tried (although technically perhaps they are also tried since you never have 100% assurance that you're not going to have a hear attack or throw out your back while you try to pick up that pebble), but the overall goal is tried for. Nothing worth noting can be done without first trying to do it. So don't go around telling people not to "try," you're just being counterproductive.
End of rant.