THREE RHYMING RIDDLES

1)
To be here is unpleasant, that's for sure;
Life is hidden, often a blur
But add an "s" and things change so fast,
Sweet replaces heat, of the now recent past.

2)
Against my grip you may resist,
But in the end you must desist;
Love me or hate me, I'm undeterred,
In the end I'll have my third.

3)
A horse that will never run,
A dream when there is no sun.

Answers:

1. Desert - dessert
2. Sleep
3. Nightmare