The shower in my house has a mind of its own.
My shower either:
1. Has good hot water pressure and great cold water pressure
2. Poor hot water pressure and great cold water pressure
3. No hot water at all and great cold water pressure

The last two mornings I have had #3, no hot water. The hot water comes out in the kitchen and the washing machine just fine.

What can I do to correct the problem in my shower??