I'm not saying this as a remedy, it's something that many people I've share it with have found benefits.
Please check with your doctor if this is okay.
It's nothing fancy just sitting or laying down and intentionally taking deep slow breaths.
Recommended doing with eyes closed.
Imagine pulling air down into your pelvis (obviously this isn't really happening it's to help get the muscles to activate) the air will slowly fill from the bottom up. Your torso will start expanding, your chest will puff out and then your head will fill in fresh oxygen. Then slowly release all the air relaxing into the chair or bed. repeat 10 times.
Both in breath and out breath should be smooth with no strain. It's common at first if muscles are jerking a little bit and the breath isn't smooth.
Once you get comfortable with that you can do a very short hold at the top and bottom of your breath.
You can then move onto box breathing.
Box breathing is proven to move us from the sympathetic nervous system to the parasympathetic nervous system. Meaning from fight or flight to relaxed. Often we are walking around with low level stress we are unaware of, this process can get rid of it.
If you are going to do a 6 count it would work like this.
Slowly inhale for a 6 seconds, hold for 6 seconds, exhale for 6 seconds, pause for 6 seconds. that's 1 cycle do 6 cycles.
Think of tracing the 4 sides of a box for each step.
The timing of this one can be tricky to get the hang of. Many people teach at 4 seconds I was taught at 7. I've found that doing too short an interval at first doesn't do anyone any favors. Starting a little too long, having a small struggle, droping the count a second and trying again until completion offers positive results a vast majority of the time.
My mom has a leaky valve in her heart and she finds breath work to help when she isn't feeling 100%
Check with you doctor as breath work can stress your heart.