You can take a language class rather than have a personal instructor. Although accents are a sensitive topic so I don't remember mine going into it much.
As someone who took English classes for years growing up, I wish that were the case. In fact, most teachers don't really know how to teach pronunciation. Also, in a typical group class setting, it's challenging to give each student one-on-one feedback. On BoldVoice, we solve that with 1) unlimited instant feedback from sound-level AI - your most patient coach. 2) in-depth video lessons from the best coaches in the world (Hollywood accent coaches). I'm a cofounder of BoldVoice, by the way. :)
Try learning a language where they won't understand you with a foreign accent. I assume tonal languages are like this but haven't tried learning any.
Japanese is sort of like this - you have to say foreign words the Japanese way very forcibly, to the point that Americans will think you're being racist if they hear you do it.