It's a common issue. Do not sleep on a shoulder/side (you may be able to do it for short periods of time, but you'll likely end up restricting circulation etc and wake up).
Sleep on your back (you just need to set it up comfortably) or stomach (may require special pillow setup...)... In general, have a good mattress (must not be soft... You'll just sink in and end up with all kinds of back pain, but too hard and you'll cut off circulation to your hands etc no matter how you lie...), get creative with your pillows... Some half-turned positions work as well...
You could possibly sleep on your shoulder if you went really crazy with pillow stacking under the arm and head but it's too much of a bother and awkward as fuck.
Weighing a lot doesn't help here, but it's definitely possible to sleep just fine... You just need to put some thought and initial preparation into it.
FWIW you don't need to have wide shoulders or even weigh all that much to end up with such issues. I've had that since I was 170 or 180 or whatever, and I certainly wasn't wide then, or even heavy for my height.
I know a lot of old people who have such issues but they just complain about it while being too lazy to make an effort to change anything... coughDAD*cough*