People read interesting things...

...and you can sell your services or products at the same time.

It's important that you share. Give people information. And if they like that information, it may spur them on to buy your service. This is the brave new world of marketing and advertising - content marketing. Really, the days of in-your-face, unwanted advertising are over. Advertising is still useful for brand awareness, but what will really encourage your customers is a story. Something useful. Something entertaining.
If you hit your customers with annoying ads, guess what, they'll get annoyed. Annoyed customers are not paying customers. Paying customers are what you want. But you need their permission first. The permission to ask for their custom. That means giving them something first. In the modern era, that thing is information. So you need to tell them a story, give them some insight, tell them about your day, share a report, be generous with information, and ONLY THEN tell them how awesome you are at fixing whatever problem they have (especially if you've just created that problem for them, a classic sales technique that even in 2016 still works).

Yes, it is a little more time consuming than shouting "BUY MY PRODUCT/SERVICE!" from the rooftops, but it is far more effective, and arguably the only way to cut through the noise these days. After all, the best viral marketing gets people involved and wanting to share without any further prompting at all. Give them a reason to share what you say, and spread your word. That's where products and services fly.