1. Rhyming dictionaries - Tons of these exist, but my personal favorite is my pocket-sized Random House dictionary. It's light and portable and gives me lots of options. It's also easy to find phonemes in the book. I bought another one, The Complete Rhyming Dictionary when I thought I'd lost my little one. It's edited by Clement Wood, which is pretty cool, but it's so big and bulky (for a paperback) that I tend not to carry it around much.
2. Speaking of not having to carry extra stuff around, there are, of course, some online options. I have an app called RhymeFree with an orange on the app image--I assume because it's so difficult to rhyme anything with "orange." It's so-so, only giving a handful of words I could already come up with myself. Of course, if I'm working on my laptop, I use Rhymezone, a decent online dictionary.
3. What I find almost more useful than rhyming dictionaries is a good thesaurus. What I love about this particular one (Roget's 21st Century) is that most entries are linked to a category word in the back, which gives many more synonym options. For example, today I was looking for a synonym for "dash," or "dart," the verb. This thesaurus then pointed me to a category of words in the index for quick movement of a body. So I got lots of other options: bolt, bounce, bustle, flash, hurtle, hustle, and so on.
Update on writing the morning pages: it's really an interesting experience. Julia Cameron said it best when she intimated that writers can get too wrapped up in their own language to successfully write the morning pages. I want what I put--even in my journal that no one else sees--to be perfect, to somehow be great art, to secretly be composing the great American novel even as I write what seems to be innocuous stuff. But what is freeing about the morning pages is that I can get out all the negative, terrible, no good writing, staple it and stick it away in an envelope. The rest of the day, then, is freed to compose something better. I'm still a work in progress, because I only managed 4 out of the last 6 mornings, and mornings and I do not always get along very well. But I can feel the practice making a difference, however slight. I'm sticking with it.