I know Chashuva Yidden who if they hear the slightest hint of Lashon Hara, they go wild and shut you down immediately. They are actually justified, since Lashon Hara is truly poison. There are many of us who habitually are always telling themselves negative self-talk. ‘I did this wrong, and that wrong’. ‘I’m no good’. ‘I’m not with it’. ‘Not frum enough/ or nice enough. ‘My smile is no good’! There is no end to this!
If Lashon Hara about others is evil, and thinking negative thoughts about others is a bad Midda, surely we need to remember to guard ourselves from those negative self-talk thoughts, with as much vigilance as Lashon Hara, and scream to yourself: ‘No more self-bashing, it’s poison!’ חַיֶיךָ קוֹאְדְמִים (ב"מ סב א) Your life comes first!
When you work on this and do plenty Pratim, it is very exciting; and your trapped true-self comes out and you blossom! Of course, the main thing is to daven for success in your Avoda, and consult with Baalei Mussar who have experience with this.