For the boy on the bike I used the motion blur to give the feeling of movement, using these steps in Photoshop:
- Extract the subject.
- Duplicate the extraction layer.
- Move the bottom layer away from the top layer in the opposite direction of the movement. In this case, the boy was moving forward, so I moved the bottom layer backwards.
- Make sure the bottom layer is highlighted and choose Filter > Blur > Motion Blur.
- Change the angle to the direction of the movement and move the "Distance" slider until you are happy with the result. Mine was 289 pixels. Click "OK".
- Move the bottom layer a little more until you get it into the spot that looks the best.