upvoting this as it is one of the most persistent frustrations that none of the data aggregators seems to solve easily.

This can be very general, like "I wish someone had told me that the work is 90% persistence."  

Be patient and persistent.  

And I'll be sure to be persistent. 

Plan, focus, patience, persistence, win.

You know how being persistent and to take action to do this.  

Just be persistent with that method. 

Do not give up and be persistent.  

You have to develop relationships and be persistent.

You have a much better chance of connecting with an owner if you are persistent rather then doing mass mailings hoping to hit that one owner who is ready to sell at the exact moment they received your post card.