This may sound simple, but what's worked well for me is to "boomerang" (i.e. return this email again tomorrow morning) myself an email every morning reminding me to meditate for 20 minutes.

It works well with my procrastinating mindset because, even if I miss a day, I never do not boomerang the email to myself. It's important to learn to forgive yourself if you miss a day, which is why it works for me.

I also always zero my inbox which means I can't miss the email.