Look for someone you know who has been disappointed or is going through a tough moment in life. Showing interest can be very encouraging. It doesn't matter if there is anything you can do to improve or fix the situation. Your encouragement will help give hope to that person knowing that there is someone who cares.
Look for someone who has been a positive influence. You might look up to this person. I don't believe there is any better way to be encouraged than to hear from someone that you were incredibly helpful in some way. Your encouragement will help inspire that person to be a positive influence on others just as he or she was for you.
Look for someone who is putting in a great effort or doing a great job at something. It does not have to be something you are benefiting from. You just have to notice it and show an interest. Your encouragement will support the actions of that individual and may give him or her strength to do even greater things in the future.
Plan to be an encouraging person to at least one person today. Inspire that person in your conversations, write an encouraging note, or help him or her in some way. You will find yourself being invigorated at the same time through your kind act.