Answer:
When young, I am sweet in the sun. When middle-aged, I make you gay. When old, I am valued more than ever.
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
What instrument can make any sound and be heart, but not touched or seen?
I am the heart that does not beat. If cut, I bleed without blood. I can fly, but have no wings. I can float, but have no fins. I can sing, but have no mouth.
Runs smoother than any rhyme, loves to fall but cannot climb!
I have two eyes in the front and a lot of eyes on my tail