When do you praise your team members? Have you ever found yourself saying "I'll remember to thank her at the next team meeting"? Did you get round to delivering that thanks? Could you remember the specific details of what your team member had achieved?
As soon as your team member completes a great piece of work the clock starts ticking, and every minute, every day that goes by the power of the praise you can offer diminishes.
Even though your day is busy, if you see a great piece of work jump on it, and take a moment to praise your team member, publicly if you can.
Use the specifics of the task they have just completed so they see that you really truly understand and appreciate what they have just done. Do it now, while it's still fresh in your mind.