Hey there...I've been playing for a lot of years and about a year ago I started to develop some pretty painful sensations in my wrist from playing. Soon thereafter, it was made apparent to me that I play with a tremendous amount of tension in my wrist/shoulders/ forearm/ fingers, etc. I realize I need to reteach myself to play without tension, but my attempts to do so up to this point have been futile. If I try to play a song normal speed and tell myself not to have tension, within 3 seconds I'm back to clenching just as hard again. The muscle memory just holds on sooooo tightly. I've conditioned myself to play improperly for 12 whole years!

So I'm trying to create a regimen for reteaching myself. I feel like I need to start playing things ultra slow...maybe go back to scales at a very slow pace and only play them at whatever speed I can without any tension. I plan to do this as a half hour warmup each day....playing only without any tension (before i spend however much time playing at normal speeds where I know I'll most likely tense up to a large degree yet again). Hopefully over time this will reteach me to play without any tension at all. I'm wondering what people think of this approach and if anyone has any other suggestions on how best to reteach myself to play without tension....Thank you so much...
Start with getting into the right position. Find a relaxed way to sit/stand so that you can get both hands in their right place without tension. After that, I'd say start with just picking as slow as necessary to get the least possible amount of tension. Start with the easiest ways.. (like starting with only one string)
Be especially careful with the right hand as you will get thousands of repetitions a day easily with it.. Keep at it for 21 days and I doubt it'll be too difficult afterwards.

For relaxing the right hand remember that even if you pick from the wrist you're not supposed to hold everything still. If they need to move so that you can be relaxed, let them move. Practice with only the right hand a lot so that you can concentrate on it 100%

For the left hand, start by learning to move only one finger at a time with the whole arm again as relaxed as possible.

A great way in my opinion to correct your technique is to go back to your already memorized repertoire and just go through every part and find a part that gives you tension and practice that.. And move on to the next one. Practice in very short segments!

Also, end your practice with a couple of minutes of Perfect ! technique practice so that your brain remembers the perfect movement instead of the less perfect ones.