The day prior to the accident flight, the pilot landed at the private grass airstrip that was no longer maintained. The airstrip had a 2,600 foot long runway with 2 to 3 foot tall grass the length of the runway. On the day of the accident flight, the pilot twice attempted to depart the overgrown runway using a “short-field” takeoff technique. During the first takeoff, he exceeded his predetermined “No-Go” point on the runway and aborted the takeoff. On the second takeoff, the airplane attained 60 to 65 mph and lifted off the ground, but settled back on the runway past the “No-Go” point. The pilot was unable to stop the airplane before it went off the end of the runway and impacted trees. The pilot reported that there was no malfunction or system failure of the airplane before the accident.