Appreciated people always do more than expected and beyond their ability too. This is how the human nature is and appreciation is a big encouragement.
At the same time, I do not mean people only work for appreciation always but appreciation about their work increases their ability. So when someone is trying to do something let's appreciate them so they definitely do it much better and succeed.
In general team leaders can use this appreciation tool to motivate his colleagues and subordinates. Appreciation gives lot of positive energy.
But sometimes if somebody is getting appreciated too much it may bring in over confidence and person may think he is doing a lot. He may become complacent. So always appreciation should be there but with in the limits.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease