It had been any other day for you up to this point. You had been at work and you were making your way back home. That's when you had been hit by a runaway motorbike, some poor shmuck had fallen off their bike and it was still going by itself, until it hit you.
Your body was flung probably 20 meters or more from the force of impact and you landed on a concrete roadblock. Your body was more or less turned into mush. You were out cold, more or less dead. An ambulance was at the scene in almost an instance and your broken body was taken away.
"Yes, this will do" one of the personnel said. "The brain can be harvested. It's in almost mint condition, a miracle." Your brain was masterfully harvested right there in the ambulance of questionable authenticity and origin. While you had been extremely unlucky that day, you had also been extremely lucky - as you were about to be brought to a secret government lab. Where they experimented with transplanting brains into new bodies, so the rich and powerful could live on forever in new young bodies.