Task: Story Composition
Input (English): Premise: Dave wanted to feel young again. 
 Initial Context: He rode bikes and lifted weights. 
 Original Ending: Dave was fairly fit for a grandfather. There were days that he could not keep up with his grandchildren. Dave felt he was getting old. 
 Counterfactual Context: He went to the doctor to get a youth serum.
Output (English): Dave was now very fit for a grandfather. He even could keep up with his grandchildren. Dave felt like he was young again.