A proof of concept is an exercise in which work is focused on determining whether an idea can be turned into a reality. A proof of concept is meant to determine the feasibility of the idea or to verify that the idea will function as envisioned. As soon as the proof of concept is in place, all the motivation to close the sale is already there. All the energy you need to have that sale cross the line in the right way at the right time is also in your hands.