For anyone that's given up on meditation

Stims as in fidgeting and fidget toys? Or stims as in amphetamine you bought on the black market?

Methylphenidate that I have a prescription for does work well enough to follow through on mindful meditation.
I am on the spectrum of aphantasia where picturing something I haven't seen before doesn't work and most things are still formless conceptual ideas, so the meditation that requires picturing something in my mind still doesn't work. But I can focus long enough to understand why!
- Can you feel the air moving into your nose or mouth?
- Oh, interesting! I'm unmedicated and I have severe aphantasia too, visualizing anything more than a shadowy figure/outline that barely moves is a completely hopeless task.
  I try to imagine physical sensations (e.g., a light breeze, ocean waves, etc.) instead, but the effectiveness of the actual meditation isn't great. I've actually had a lot of success with relaxation by way of hypnosis videos on YouTube, though.
Methylphenidate, it's made for adhd
- I totally misread the title of your post as 'medication' as opposed to 'meditation', apologies.

I've gotten a few vocal/chanting meditations from my therapist, it's like a guided meditation but you chant a few words repetitively along with the recording and move a bit in rhythm to it. Stuff like make circling motions with your hands (on chest/stomach or in the air), or tap thumbs to each of your other four fingers, or sway your upper body while sitting still with closed eyes. Pick one movement and follow along with the recording.

It works so much better than being quiet and still. First time I actually finished a meditation and felt better afterwards instead of frustrated and bored. I still lost focus a few times but it felt more like a normal persons struggle to meditate than the impossible task it usually is.

The movement thing is fascinating, because the swaying (besides also twirling my hair) are ways I already stim.
Do you think you could send them to me?
- You could find any musical chant and make up your own repetitive movement, but such possibilities tend to overwhelm me, so these are the ones I got recommended to me, with links to Spotify and YouTube:
  Touch your thumbs to your fingers in the order 1 2 3 4 4 3 2 1 1 2...and so on. Spotify - Sa Ta Na Ma
  Place your hands crossed over your chest or one hand in chest and one on stomach, optional to sway back-and-forth, in a circle, or be still. Spotify - Ma
  Move your hands up and down like this Video of the movement. Spotify - Sa Re Sa Sa
  Of course you can also mix and match movements and chants as you please.
  I've done them sitting on the floor with legs folded (you can put a pillow or folded blanked under the back half of your butt to get your knees a bit lower and feel steadier) with back if the hands resting on the legs, but they could be done standing, lying on your back, or on a chair as well. Keep your back straight and your head aligned so it's not tilted up or hanging down, and try to relax your arms (and face, or wherever you're usually tense). Turn the volume up and dare to chant loudly, feel the vibration of your voice in your chest.
  EDIT: It might be in order with a warning here, as these practices often run parallel to cults, so be aware not to be sucked into spirituality that leans into glorifying or following one or a few strong leaders, or glorifying the practises over your own experience of the practice. The artist in two of the three above songs for example, was part of and has now left a Kundalini Yoga (KY) and Sikh cult.
  Practice these things for your mental health and to calm and center yourself, but don't fall into the extreme of striving for any sort of purity or perfecting balance or perfect whatever. These practices should support you and help you feel better - you are not here to support them, and there is NO way in which you can fail them because they are your tools to use or not use at your own discretion.
  I personally always skip or ignore the spiritual babble in any type of yoga because it makes me uncomfortable, and just do the fun parts. I also recommend removing these types of videos from your watch history or watch without logging in, otherwise your YouTube feed will be flooded with spiritual grifters videos.

Mantras work well for me

What konds of mantras?
- Like the others shared here I too have aphantasia. But I do have a vivid auditive imagination.
  So I often play tunes in my head on repeat. For example: the first 25 seconds of this song, the part before the vocals. It's short, so when I recognise my thoughts wandered, I just restart.

Also, it helps to do it staring out of the window when travelling or while watching someone work.