How do you handle strangers trying to state you down or looking at you with envy?

When I go to the gym for example, some people (mostly younger people, not always) try to stare at me or give me smirks or slightly pissed off looks. I'm an unusually attractive guy so I know that's just some people's defensive reactions but I don't have friends at the moment so these common occurrances really trigger my anxiety which then blocks my common sense and makes it feel like it's a WAY bigger deal than it is, when it's just strangers that don't know me looking at me. I know it's just my amygdala going haywire but; How do you handle it? It's also hard for me to accept so many people behave in such immature ways.