I'm 42 and because I live in a college town a lot of guys I play soccer and basketball with—and run with—are in their early twenties or even late teens. If you're turning thirty and overall fit, I think you have little to worry about, but consider the following:
—you may find as you age your recovery takes longer
—recovery from injuries like an IT band injury will almost surely take longer and require proactive PT.
—your shoes are something you'll pay more attention to, especially in general fit. As we age, our feet and especially toes tend to spread so it's not uncommon to go up a half to full size in your mid to later thirties. I did.
—You can do what you want to do, barring exceptional injury, for a very long time. There are masters competitors in hurdles, pole volt, and other very demanding track events.
—falling feels differently to me now: I was watching a high school soccer game and saw kids constantly trip or take a spill and bounce back up. When I play soccer I admitted don't bound back up as fast.
—consider tai-chi or martial arts as you age for improving flexibility and balance.