Answer:
Sometimes you feel it weigh a ton. Yet it is nothing, but somehow still there. Makes you uncomfortable around anyone, But speak its name and it's gone.
You do this into someone's ear when you want to be discreet.
Some adults still use these to count.
Four kings of whom I am one lord. Often on deck but never on board. Though I have a large heart, I am always seen at war. During which I always wear a suit, but never a suit of armor. Who or what am I?
Its days are numbered.
In birth I spring forth, in life I unfold. In death I wilt and die, but rebirth restores all.