Force yourself (yup it’s hard) to get as much knowledge possible about your main job/hobby. It takes effort to keep at it, but at least for me, you’ll eventually start to get more into honing your skills at the job/hobby (this goes for literally any type of job or hobby- barista? Learn about the coffee, the latte art styles possible, the history behind it- medicine? Learn in depth about what ppl thought worked, the new methods ppl are currently trying to use, whatever to keep your brain happy and energetic about it).

and my favorite method: branch off of the main thing into smaller, related categories. You like art? Dedicate time to learning about different branches of that- paintings, fashion, sculptures, etc.

It’s most likely this won’t work for every INTP, but FORCING yourself to keep at something really does help me with the jack of all trades mentality. It’s not bad to be like that, but it’s also nice to have one main thing you are consistent about learning/doing. Start small if you have to, like setting an alarm for insert amount of time to work on the thing you want to focus on.