Answer:
To be very impatient
Explanation:
Richard III is a play written by William Shakespeare.
In the given context, the phrase means 'to be very impatient'.
Richard is waiting eagerly for the death of his brothers so that he could inherit the throne. But the planning that he is making, i.e. to get married to Warwick's youngest daughter, Lady Anne.
The phrase "I run before my horse to market" implies that Richard is being very impatient for his plan to succeed.
So, the correct answer is "to be very impatient".