TMJ: How can I reduce my clenching at night?

I have been clenching my teeth for decades. I experience constant facial pain, headaches, neck and shoulder pain, ear ringing, plus other symptoms. I wear a mouth guard though sometimes I need to take it out when I can’t sleep with it in. The biggest area of pain is in my left cheek and left shoulder, I’m pretty sure they’re both related. It seems to never end and I was wondering if anyone whose in their forties or fifties still clench? Will it ever get better or is it something that’ll continue forever? How can I reduce the amount of clenching at night?

Any help would be appreciated. Thank you. Rob