How Do I Improve My Running as an Experienced Athlete in My 50s?

If you’ve been running for years, this thought may sound familiar: “I feel like there’s something more in me… I just haven’t really tried to find it yet." You want to see what you’re capable of but at the same time, you’re cautious. Because now, every push comes with a question mark. - Will this flare up my knee? - Why do my hamstrings tighten late in the run? - Am I actually training right… or…