You show a small envelope to your spectatorindicating that you have a prediction inside the envelope
You ask the spectator to cut your deck of cards into 2 parts and then ask you to designate a part of deck; You ask the spectator to distribute the cards one by one to make 4 small packets.
Then give him the 4 cards above each of the small packets and ask him to choose a card by pointing it with his finger.
Replace the cards not chosen on the deck and turn the card of the spectator (for example king of heart) take out your prediction of the envelope, it corresponds to the chosen card.
Finally explain that the spectator was influenced by this card because he could not choose another card, you spread the deck face up and your spectator will see that your deck of cards is totally blank and he chose the only printed card.