tl;dr - If you lift weights or do anything else in the gym where you regularly count (in your head or out loud)… why aren’t you doing it in Japanese???
I have no idea if this has been discussed before. It seems simultaneously simple and brilliant, and I’m kind of mad I only just thought of it now after wasting an entire year not doing it.
After ~1 year studying Bunpro and Wanikani, and only more recently starting to try to focus on listening exercises because I realized how much I suck there, I am astonished to find how often my brain crashes mid sentence when I hear either:
- a katakana word, even if it is borrowed from a common English word (I am aware this is common)
- a long number (e.g. 3,456) or a few short numbers (e.g. Nov 12 @ 2:35pm)
The number thing drives me crazy because (a) I’m a math nerd and (b) numbers are like the first thing you learn (so shouldn’t they be… easy)! Clearly, in order for me to parse long number strings more quickly, my brain needs to be more hardwired to recognize every one of the 10 base numbers lightning fast.
The conclusion, which has already been spoiled: I work out several days per week, and I count to 12 for most of my sets. I’ve always found the counting boring and painstaking, but I do it because I need to keep track. Well, now I do it in Japanese, and it’s a tiny bit less boring, and (presumably) a lot more profitable! (And maybe also I can pretend I’m a karate master training to save the world).
I’m also trying to force myself not to immediately imagine the English translation in my head. E.g. when I say 六, I try not to picture “6” or “six” in my head… instead I try to picture 
(3 fingers, times two), or maybe even ⚅ (six dots on die face).
I have not seen major profits from this change (yet)… but here I am giving you all advice anyway. 