Is there an indication that the action needs to be taken now? The tone of the presentation, offers and deadlines can all influence urgency. I bet you have seen urgency notifications like this before:

There's 2 kinds of of scarcity you can create:

• quantity-related scarcity (2 seats left at this price)
• time-related scarcity (last day to buy)

If the supply of your product is endless, you can give out time-sensitive bonuses, a free gift to first X amount of buyers or a discount if they complete the purchase within a certain time frame.