You know you're supposed to be exercising or whatever. But there's no issues yet. You're doing fine. That cheeseburger won't kill you. Heart disease is for old people. You can eat whatever you want.
But you know better. Quality training helps prevent all sorts of terrible things, like easily broken bones, loss of jar-opening-powers, stroke, heart attack, etc. they just haven't happened yet.
Simply from an enjoyment perspective, start now. Not in 5 years, not in 20. Start now when you have time to explore and find the kind of training you enjoy.
Maybe you tried doing cardio by running on a treadmill and wanted to kill yourself. Maybe you tried a rowing machine but threw out your back so you swore that off. Maybe you heard that free weights are dangerous or you'll bulk up too fast.
Whatever your hurdle is to leveling up your body, we'll find a way around it. We'll find something sustainable and worthwhile to make sure you can keep eating that cheeseburger.