Forget what you've been told about sitting cross-legged for twenty minutes and attempting for a "blank mind." That sentence alone was written by someone whose brain has only a handful of tabs open at once, https://themindfulcounselor.me/blog/do-you-have-to-sit-cross-legged-to-meditate.
The ADHD brain feeds on dopamine, novelty, and a stream of sensory information — so the opposite of those things (calm, quiet, repetition) when asked of us, would in most people cause them to feel not good enough, like everyone else would; but also feel like a massive letdown. Which, again, does not ever come from willpower — it comes from improper usage. Two minutes.
Do not try for ten.
Commit to just two minutes; which, in the first 30 seconds of which, you are going to drift off in some kind of spectacular way anyway; so with all due respect — the less runway you have when it first zooms away, the less time it has to pick up too much speed —and you can pull it back! Success is simply coming back —and this is your entire rep. When doing the rep for 50 occasions throughout two minutes,you would most certainly generate a stronger attention muscle than someone who just quietly sat for twenty minutes on the floor,totally aware of absolutely nothing.
Physical motion helps a lot; a walking practice, free-form dancing, even walking laps around the room; or literally any physical activity while attempting meditation... Any of it counts! Consider pacing the house or the room with something tactile and just tune into your breath when it wouldn't be a good situation at all,if anyone in the world were to witness your behavior! Surprisingly enough... "tidy up the kitchen" meditation (running water, hands busy and mind in its body) is frequently how the most present and intelligent minds actually find bliss with meditation instead of a picture-perfect, straight-out-of-a-yoga-magazine, meditative bliss pose.
Sound can be another lifesaver where complete quiet becomes almost unbearable in an ADHD brain. Put on your favorite guided sessions, ambient soundscapes, or even just a ticking clock in your room and your brain will do the rest by latching onto whatever thing it's listening to!
Placement of this meditation session throughout the day matters too... If you take prescription medication that you take at some point daily then this is frequently a much better time than first thing in the morning, when your brain is nowhere near ready.