All of these tools are free or have free versions. I've included things that work on desktop, but also on mobile devices if you like to create on the go. These are my favourite because of their price, their features, and their ease of use.
Full disclosure #1: these are all things that I've done personally when trying to write content with a brain stuck in first gear. I fully endorse these tips!
Full disclosure #2: this is not one of those articles that tells you to go for a walk in the forest and listen to birdsong or pop down to the yoga studio. Each one of the tips below should take as little as 10-15 minutes.