From The Lamb Himself:

Matthew Chapter 6:

5 “And when you pray, you shall not be like the hypocrites. For they love to pray standing in the synagogues and on the corners of the streets, that they may be seen by men. Assuredly, I say to you, they have their reward.

6 But you, when you pray, go into your room, and when you have shut your door, pray to your Father who is in the secret place; and your Father who sees in secret will reward you openly.

7 And when you pray, do not use vain repetitions as the heathen do. For they think that they will be heard for their many words.

8 “Therefore do not be like them. For your Father knows the things you have need of before you ask Him.

As for Tebow? I think recognizing who he owes thanks to is OK...but I too, as a Christian, have a problem with his "exhibitionism".

He could do it on the sidelines, sitting on the bench, and no one would know. That's what I get out of the above teachings...a private (not public) talk with Yahweh to give thanks...