Love this post by Jon Bell about the importance of starting somewhere, anywhere:
There’s no defined process for all creative work, but I’ve come to believe that all creative endeavors share one thing: the second step is easier than the first. Always.
That in turn reminds me of the incredibly awesome video series Everything Is A Remix. If you haven't watched them, I can't recommend them enough. If you're still not convinced, in the words of Maria Popova of Brainpickings:
Kirby Ferguson’s excellent Everything is a Remix project is, as I’ve previously written, one of the most important efforts to illuminate the mechanisms, paradoxes and central principles of creative culture in modern history.
They really ram home the notion that nothing is truly original - and that it can't possibly be. Every new idea is necessarily a transformation, a re-contextualising or a mash-up of other ideas. Acknowledging that will set you free.
Another author on this topic that I like is Austin Kleon. He covers some similar themes to the video series above. Most of his thoughts used to be available online but it looks like now you have to buy his book Steal Like An Artist.
Relatedly I also like both of Paul Arden's books: Whatever You Think, Think the Opposite and It's Not How Good You Are, It's How Good You Want To Be. They both contain some great, if pithy, insights and probably take less than 30 minutes to read.
I can't remember where I first encountered the idea that the most important first step in creation is to make a mark (e.g. start a sketch, write that first line of code...) - any mark - and to try not to judge your ideas too quickly, but it's helped me with everything I've done ever since.
Now go and watch Everything Is A Remix.