Ditch what you've been told about sitting cross-legged for twenty minutes and trying for a "blank mind." That sentence alone was written by someone whose brain has only barely a few tabs running at once, graveyard keeper meditate.
The ADHD brain thrives on dopamine, novelty, and a stream of sensory information — so the opposite of those things (calm, hush, repetition) when asked of us, would in most people cause them to feel inadequate, like everyone else would — but also feel like a massive letdown. Which, again, does not come from willpower — it comes from improper usage. Start with two minutes.
Don't reach for ten minutes.
Commit to just two minutes; which, in the first 30 seconds of which, you are going to lose it in some kind of awesome 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 bring it back! Success is simply coming back,and this is your entire rep. By doing the rep for 50 occasions throughout two minutes —you would most certainly generate greater mental focus than someone who just remained still for twenty minutes on the floor —totally disconnected from any thought.
Motion works greatly; a walking practice, free-form dancing, even wandering the house; or anything physical at all while working on mindfulness... Whatever works! Consider pacing the house or the room with a fidget object and just tune into your breath when it isn't a good situation at all,if anyone in the world were to observe your behavior! Whether you buy it or not... "clean the kitchen" meditation (running water, hands in motion and mind in its body) is more often than not how the most present, intelligent minds truly find peace with meditation instead of a picture-perfect, Instagram-worthy, meditative bliss pose.
Sound can be another lifesaver where complete quiet becomes hard to sit with in an ADHD brain. Listen to your favorite guided sessions, binaural beats, or even just a ticking clock in your room and your brain will handle the rest by latching onto whatever thing it is listening to!
Placement of this meditation session within your daily schedule matters too... Should you have prescription medication that you take at some point daily then this is frequently a much better time than early morning, when your brain is nowhere near ready.