Can I assume you’re single, and a bit discouraged by the dudes with bling & the hotties hanging on them?
Just keep the waistband of your trousers at least 4" below your bellybutton, the same waistband under 36", and no socks when wearing sandals and you’re cool…
You’re only as old as you allow yourself to be. I’m 42, and pay the price for “thinking” I’m still in my 20’s… (takes a LOT longer to heal

) What I find myself doing is applying my experiences (via time) to circumvent the impulsive “20 something go for its” and the subsequent “Oh sh*t this is gonna hurt tomorrows”…
I’m out busting it with teenagers in the Scouts one weekend every month, and they’re the ones wheezing and calling for a break on hikes! (What they don’t know is I can barely undress and crawl into the sleeping bag at night

)… but I can hold my own with the “young bucks”… and I earn their respect and the ultimate compliment “For an old dude you’re OK”.
It’s not a sin to want to be younger… I’d say it’s a sin to take surgical means to alter yourself to
appear younger… that would be a selfish act.
At 28 you’re in a transitional stage… not a carefree cruiser, and not yet accomplished man… give it a few years. Look at other men that are in their mid 30’s, that have their “act” together…you’ll understand what I mean.
Physical appearance is only a small element. A man who’s proud, confident, true, and has his life in order will have the same (in female form) clamoring for his attention… regardless if you’re bald and don’t have a six-pack gut.