Clarinets, saxes, and any other instrument that gets to use a lyre, you are all lucky little fraggers. With flute, we have both arms holding the flute up perfectly parallel to the ground (NOT an easy task, I assure you, despite common belief) and our left arm being used to hold our flip folders.
Now, that may not sound so bad, but when you carry it around like that for a while, your arm starts to hurt.
As my flute friend in marching band jokingly said, you end up with one totally normal, flabby arm and one completely ripped and muscular arm.
Is that ridiculous? Yep. And really funny when you're in the middle of practice.