How do you become a healthier SJ? Just by reading these posts recently I've discovered those nitpicky stereotypical things that other types don't like about SJs...too task-oriented, tend to micromanage, too focused, etc, and I've tried to be more laid-back and less controlling. But I don't really feel like "myself" when I do that!
You won't feel like "yourself." No one does, when they change.
So my first advice is be patient. If you change too quick, you won't 'know' yourself and will feel weird like you do now.
ESJs have a Ti/Fi inferior. They need to learn to back off and learn to make decisions either by determining and applying what something is (ESFJ, using Ti) or what it personally means to them (ESTJ, using Fi).
ISJs have an Ne inferior. Their problems usually revolve around becoming paranoid of what could happen if they don't plan well; they see lots of threat in the environment.
One thing that helps is having friends who are GOOD at those functions and getting their advice so you can recalibrate. For ISFJs and ISTJs developing Ne, trying to brainstorm and/or try new things in a "safe" environment will give them confidence when there is more risk involved.
Don't feel ashamed of your strengths. You ARE task-oriented, can manage and organize well, are focused. Some people can't do that. You are just looking for ways to ease up and enjoy yourself more.
Schedule time to "play" where you can... where there is no task to do. Take an art class or teach yourself to paint. Go for long walks and just observe nature. Try to play a song "by ear" if you are musical. Set aside $5 (or a specific amount) and go play video games at an arcade. Use your organization abilities to "plan" fun time for yourself, and when you are there, do not work; force yourself to play and not think about the clock. Go lay out in the sun with your shades and read a book.
Watch silly movies/shows and don't make fun of them or worry about the appropriateness, just let yourself laugh. Let yourself be surprised. (Part of humor is being surprised.)
Think about something a friend said and try to imagine why they might have said it, beyond the obvious. You don't need proof, just imagine every possibility you can and list them. Do this with various things, you are trying to stretch the imagination, not have the "right answer" per se. Then check with them to see how close you were.
Is this helping?