Print is often easy to sell because you bring your physical publication with you and show it to a prospect as part of the sales process. Digital is a little more challenging and ephemeral.
That said, it's also fast and easy to do mockups which don't merely show an example but help your prospects "see themselves" as the advertisers, sponsor etc.
As I've taken to say, "Without examples, nobody knows what you're talking about. Without examples that are relevant to me, I don't know what you're talking about."
Watch the video above for an example ;)