Patch Tool

Sample Output

Steps

1. Open Photoshop and get the Patch Tool. Set it to Destination and select a portion of smooth skin by dragging, as if it was a Lasso.
   
2. Drag the selected portion over a wrinkled part.
   
3. And it is unwrinkled. You can repeat step 2 if you want, or you could make a new selection from step 1.
   
4. Repeat steps 1 to 3 for each wrinkle. Don't forget the cheeks and the chin.
   

Now try the exercise.