SOS_SCHEDULER_YIELD - Prevent a Proc from giving up the Processor Time
It's impossible to do this in the procedure.  This wait type is a function of the scheduler.  Each SPID gets a finite amount of time (4ms) on the processor.  Once that time, or quantum, elapses, the SPID gets put back into the wait list until resources are available again.  This wait type is indicating that the SPID was not able to complete its work on the CPU in the quantum and had to "yield" to another waiting process.

This cannot be changed with any SQL code.  You can specify resources be prioritized for your load with Resource Governor, as Paul White suggested.  Even so, unless, as Kin suggested, you are experiencing a lot of CPU pressure, Resource Governor won't help either. 

Check for CPU intensive operations and minimize where you can.  One that bites a lot of people is the Implicit Conversion, that will quickly be discovered by scanning the execution plan.