My son is more observant than shy but a lot of people chalk it up to shy. Sometimes he'd rather watch kids play than join in, like he's just trying to figure it out.
One thing that I think helped was me not getting involved immediately when things go wrong. It used to be we'd go to the park with a soccer ball and some kid would come up and just take the ball (usually trying to play with him) or get to close to him and he would lose it, run over to me and that would be the end of it. If I was lucky we'd stay at the park and move away from the other kids.
I tried teaching him to use his "big boy bark" and now when a kid does something he really doesn't like he'll handle it himself, usually just by yelling something like "stop", "don't do that", "give me space". Usually the other kid will come up to me and ask what's wrong with him and I'll translate "he told you not to do X, maybe you can try asking him first" and it results in the other kid being a little more concious of what they're doing, and since my son can handle this stuff mostly himself he's much more open to playing with other kids and continue playing if something doesn't go his way. I can see him just letting stuff go without making a fuss now too, whether he doesn't feel like the thing is worth his effort or he doesn't want to upset his "new friend".
While writing this out I realized my 3 year old almost exclusively plays with older kids, maybe it's because they can somewhat grasp the stuff he's trying to get accross? I think whenever we play with kids his age he gets frustrated and they try to touch him a lot which he doesn't tolerate well.
Then again they're kids and I don't have a single clue what I'm doing or they're thinking. I think the big boy bark is a good tool to have though, we got the idea from a bluey episode and I just annoyed the shit out of him for a few days straight and by the end of it he was telling me exactly what he didn't like in a very clear voice
I apparently have an unhealthy relationship with food. After not having much of it for a majority of my life, now that I can afford to eat 3 meals a day I usually make those meals way to big, to the point where I make myself sick a lot.
My wife pointed out that I always need to be watching something while I eat and it's likely me trying to ignore the fact that I'm constantly panic eating as much food as possible.
I also can't stand when people talk to me or look at me while I'm eating, especially in any sort of company. My wife says I'm like a rabid dog when we go out and tries to remind me that no ones going to come up and take my food away from me. But just this evening my toddler snatched the last chocolate cookie litterally out of my mouth, although to be fair I did the same thing to him with a piece of plastic he was trying to eat a few minutes earlier.
Anyway there's my somewhat related take.