THREE RHYMING RIDDLES

1)
My first is in silly, but not in fool,
My second in pupil, but not in school.
My third is in read and also write,
My fourth in glimpse and also light.
My fifth's in ten, but not in three,
My sixth in  trim and also tree.
My whole is a race - part of a meet,
The victor's crown, a feat of the feet.

2)
Every dawn begins with me,
At dusk I'll be the first you see;
And daybreak couldn't come without
What midday centers all about.
Daisies start with me, I'm told,
And when I come I end all cold;
Though in the sun I am not found,
In round and ground you hear my sound.

3)
He who lacks it, sincerely seeks it;
He who has it, often mistreats it.

Answers:

1. SPRINT 
2. Letter D 
3. Health