From the North:
Interstate 87 south to exit 9E (Halfmoon exit). This will put you on Route 146 heading east. Route 146 ends at Route 236 where you will take a right onto Route 236. The Halfmoon Town Park is the first right, you will see signs for the MTA5K at the entrance. (If you miss the turn, there is another on the right after the first one.) Follow the road until you see the parking lot with the playground and the rest of the signs/volunteers etc.
From the South:
Interstate 87 north to exit 9. Take a right off the exit to get onto Route 146 heading east. Follow the above directions from this point.