@rachel21 & of course @carrie4, when I first started back on my path (July 2020) I had never meditated before in my life! I always stayed away from it, & came up with some excuse (usually my anxiety/panic) why I didn’t or couldn’t even try it. Then I started the courses on Spells8 & knew I had to work on getting my brain to shut off, at least try to focus for ANY length of time. My personal best at that time was 3 minutes of guided meditation 
However, I continued to practice sometimes more than once a day. But I went slow & started with 1 guided meditation until I made it through the whole thing (it was 10 minutes long). Now I can sit through up to a 25-minute guided meditation & my visualization; compared to what it was; is so much better. As of right now, guided meditations that are focused on grounding & centering are what I have been working with & a guided meditation to connect with my crystals on an energy level in a much better way than the small one I have now.
I agree with this, practice & using different techniques to help quiet the intruding thoughts so you can tap into visualization without forcing it; will come. I actually addressed my anxiety & stressors through a meditation using the app HeadSpace for a time. They had “courses” for beginners to meditation & for anxiety, financial stress, stress, sleep… they would start out easy & as you went through them without even realizing it, you have gone through the first set of the course & are moving onto the advance courses.
Now I use the app/website Insight Timer & it has so many free meditations & other mindfulness practices to help with whatever you may be working on at the time. Even though you have been meditating for years, maybe starting with a beginner’s course or meditation through an app for anxiety or mindfulness or spirituality may assist you?
I have also started using the YouTube video for a 1-minute meditation practice, the entire video is 5 minutes long, but you could use the same practice to lengthen the time that you quiet your mind for visualization with the technique they are using.