Just so you know up front - I think I have a weakness on this one, but maybe eventually... :)
Growing up (and by that I mean the first quarter century of my life) I thought of the following phrases as about the limit of encouragement:
"You look really nice"
"You're gonna do great"
and *maybe* "You could improve here"
But it's been a recent realization for me that while that stuff can be encouragement, it falls so far short of what encouragement really is, and what it really does. Those items, while they might give just enough of a confidence boost to help someone out, more often are far nearer to well meaning flattery than they are true encouragement. Don't get me wrong - words of encouragement (even such as those) can mean a lot, and are definitely encouragement in and of themselves, but I think that there is a much, much bigger picture and reality to encouragement than we find just in those.
Maybe I define it differently than most, but I look at encouragement as giving someone the ability (through words, actions, or lifestyle) to accomplish something they couldn't have without you. This definition does a couple cool things for me:
1) It keeps me from viewing what I do and say through such a myopic lens, especially in terms of encouragement being a positive cliche here and there
Meaning? I have to be aware that true encouragement (given my definition) comes through an intense process of recognizing and meeting needs in terms of the Christian walks of those around me.
When someone is feeling guilt and shame, they need a reminder of who they are, who their Lord is, and what that means. That this unbelievable grace and mercy we've been given has covered them. You have to ask questions and truly attempt to perceive to discover those feelings in someone usually - but that is the depth of true encouragement - without knowledge and wisdom, how can we know where and how to push?
When a brother is floundering in sin - I have to recognize it and address it in a way that can help. This doesn't mean nagging (why don't you do X), or stating the obvious (you just gotta follow Christ better, man). It doesn't mean we talk about it because it benefits me for him to be better (i.e. he has some anger issues that are affecting me negatively, so we need to talk them through because I've been wronged).
It means that I have to see the sin, and approach him about it in a loving and humble way that spurs him to be more and centers him on Christ. Because the reality is this - even if his sin has negative effects on me, it doesn't rob me of joy. But it is killing him, his relationship with Christ, and his relationship with others. Knowing that, it's way easier to care and love instead of feel offended and attack. Knowing that leads to an encouraging reproach... instead of just nagging (which does nothing but promote insecurity and anger, even if it gets 'results').
When someone does something right that I appreciate, I should absolutely let them know. Dating is the easiest place for me to illustrate this (probably marriage would be better, but someone else would have to chime in there). I've spent 25 years of my life viewing boy/girl relations as a competition - because frankly, that's what it's been. Girl wants control, I want freedom (see: Genesis). Girl wants me to do better for her so she points out my weaknesses, I point out my strengths or her weaknesses to balance. Girl has a plan that I know based on her actions won't work, I do it perfectly to prove that I'm right and show her my way was better and she can shove it. Why is all this cycling down the toilet this way? Because both of us are far more worried about ourselves than each other or Christ. How is this related to encouragement? I have no idea (kidding). The reality of encouragement is this - there is only one better way for us to pursue in the universe - God's. So encouragement is the active art of pushing someone towards God (something better), and you know what I've discovered lately? If someone surrenders that need for an illusion of control and tells me "Hey, I really appreciate the way you do this for me" - I instantaneously do better. Because I WANT to. When you know what you do is appreciated, it is natural to try to do it even better. In the prior circumstances listed here - I was told what I was doing wrong so that I would solve it because someone else felt (and probably was) wronged. But it never mattered how good I might be outside of that, which meant what? That I'd insecurely justify my wrongness with theirs and at best would perform out of either obligation or a smug "we'll see about that" attitude. In that second approach... I did better because I wanted to. Because that encouragement and trust made me love that person all the more. Encouragement from the mouth of a woman has a very powerful effect on the heart of a man, ladies - learn that and stick to your standards and you will both find, and help create, that man you've been searching for. If you don't understand that - I suspect you're going to find a lot more conflict, insecurity, and anger in life than you suspect. Emotionally bludgeoning for results does not change the realities behind the shortcomings, it just builds a wall in your relationship - even if you get what you think you want. Neither of you will ever be fulfilled or fruitful because in the end, it's all about you and your need to be treated perfectly.
2) It reminds me that encouragement doesn't happen just through my singular moments (a phrase), it happens through my lifestyle
My actions (not just words, thoughts, and strategies) encourage people. You see me loving, you want to love and it shows you a way to do it. You are a recipient of my love, it gives you a way to improve (think giving someone very poor and unemployed a job so that they can feed their kids... or other items like that) so that you can spin that lifestyle right around and encourage others through it. Not to mention both these establish trust in the relationship with any people involved (because you know that the individual who is loving will try to put you before themselves). When you receive a gift, do you treat it better than something you buy? Heck, I know I do. So it would serve to reason that any gift (money, time, words) has the ability to encourage some one onwards and upwards.
Will encouragement always lead to someone finding a strength, peace, or joy that they lacked before? Probably not, but that has nothing to do with whether or not we should do it. Is encouragement still way bigger than a good old fashioned butt pat and a "You'll get 'em next time" - yeah... yeah it is. It is a foundation of trust in our relationships. The evidence that we love another more than ourselves. And hopefully, one day, it will be so ingrained in us that people will use it as proof of what defines us - Love.