I found the best way to do this was to run to the first Star Post in Green Hill Act 1 then stop just before you run past it. Hold down
and hammer
to build up some momentum before releasing.
It took a few moments for the achievement to pop (right after I ran through the second Star Post).
Despite what the description says, I don't think it's a matter of grinding as I'd definitely run past way more than 10 Star Posts before it popped trying this method on a 'No Save' file.