When the eagle soars, he doesn’t have to work. The shape of his wings and his momentum are what provide the lift along with the rising air currents. All he has to do is extend his wings and float, so of course he’s not going to get tired. He’s just lying there...Resting. Waiting. Letting other forces carry him along.
We like to flap our wings. It feels good and strong to flap flap flap and suddenly, wow! you gain a bit of speed and lift and you’re flying. Only to fall back to earth panting, dazed and exhausted. But oh, that bit when you were in the air – stimulating in the extreme. Flapping comes naturally to us.
By contrast the eagle most often begins his flight by jumping off a cliff. The very last thing we want to do! Jumping off cliffs does not come at all naturally.
The analogy continues as you consider that the shape of the eagle's wings is the way God made him to be, tools he’s been given that he had no say over and did not make. For us, that would be all the things God has given us at salvation in the spiritual realm, including the filling of the Spirit -- and the means of regaining it when we sin -- and His word. The eagle’s momentum comes from flying – from jumping off the cliff and gliding away. After he has glided a bit, he flaps his wings to gain more altitude so he can float some more. For us, flying would be learning the doctrine (flapping – because it does take effort to learn), believing it, then applying it to the circumstances of our lives. Which leads to rest. So... flapping is learning and applying the word to our lives, while floating is the result of that application.
An hour a day listening to/reading the teaching of your pastor. 23 hours resting in what you've learned. No wonder the soaring eagle doesn't get tired.