You don’t have to create material for your content marketing on your own. Not only can you look to those who have gone before you for inspiration, you can actually build your content around their content.
For example, as you are researching a topic, you may find an article that outlines the argument you want to make as perfectly as you can imagine. Copying the article word for word is an enormous no-no, but you can certainly model the main points of your article after the main points of the existing article. You simply have to put those arguments into your own words. (And, I would add, cite the original article if you include any data, research, or examples the article uses.)
Better than that, though, is citing the entire article and adding your own take on its arguments and conclusions. This works well not only for you and your target audience, but also for the original author. You get great content with less effort than you might expend otherwise. Your audience gets the benefit of that great content. And the colleague or competitor who wrote the original gets the link and exposure to help build his or her audience reach and SEO “juice.”

You also may gain a fan in that original author, which can lead to social media mentions of your post, since the source author is likely to be proud that his/her work has been picked up. It can also lead to reciprocal links and mentions. We’ve even created relationships with colleagues we’ve met this way that have led to referrals and collaboration.
So don’t go it alone, particularly as you’re getting started and may not yet feel you’ve got a handle on what the scope of your content should be. Make the most of the resources you have by leveraging great work that already exists. (Just be sure to do so ethically.)
image credit: By Masur [CC BY-SA 3.0], via Wikimedia Commons