@Dontgiveup For me I feel muscle stiffness and tense after specially sitting long hours in front of the computer working. All my muscles feel tightened, my right side is bit worse. What I found to have worked with muscle tenseness is, wearing SOFT NECK COLLAR and Transdermal Magnesium Spray around the tense muscles such the traps and the neck muscles (Magnesium Spray is itchy so beware). The magnesium spray reduces and relaxes muscles spasms. the Soft Neck Collar keep your neck straight and I hypothesize that it helps not to further collapse the IJV thus collaterals don’t swell too much to cause spinal issues such as stiffness, weakness…etc.
I also find cold shower (I know you are already getting goosebumps hearing it) and Sauna heat helps as it relaxes the whole body. I usually take cold shower after the Sauna. If you need to know other benefits of cold showers, we talked about it here (Cold showers - #4 by KoolDude)