I am posting this on blind handyman  and blind hams list as it applys both 
places.  I may have missed a post as one person mentioned using water, but I 
didn't find the explanation.  If I may provide that and hope it is not 
duplicating.  Since the rod clamp and top of the rod needs to be below 
ground dig a hole 18 to 24 inches deep and big enough to work a wrench in. 
Stab the rod into the bottom of this hole a few times withdrawing it. 
Wiggleing it around may help.  Take it out fill the small hole with water, 
Letting it set a few seconds may help.  Again jab the rod in this water 
filled hol .  Each time it will go farther down.  Repeat the process filling 
the small hole with water  Jabbing it up and down.  When you can not pull 
the rod out then and only the get a hammer.  I usually can get a 8 foot rod 
down half way or 4 foot and if my work hole is only 12 inches I am only 
driving the rod 3 feet.  And with the residual water it goes easier than all 
dry dirt.  Early on you can wiggle the rod some and pour water around it 
between pounding attempts.
73
Ron.
This water jetting procedure can also be used to put lines, water, gas, 
electric, or communication under sidewalks or driveways.  In those cases a 
pipe is set up so water comes out the boring end a valve to control the 
water flow is necessary..  The driving  drilling pipe is usually left under 
the sidewalk as a conduet..  Beats the heck out of saw cutting concrete.