If your goal is to run a 5k without your knee hurting, that to me is health. If your goal is to shave 5 min off your 5k, that's performance. Go to the gym and do some pull ups without your elbows hurting, health, compete at the Crossfit open without your elbows hurting, performance.
Often times health is simply removing some of the
stupidity, misinformation that is out there. How many times have I simply stopped someone with a flexion intolerant back from doing hundreds of sit ups each day. "I was told my core is weak, sit ups strengthen the core."
"I want to lose weight, so I started running." Do you enjoy running? "No, but it's the only thing that will keep my weight off."
Weight is 90% of what we eat. There is so much misinformation about food and eating though, I can understand the confusion. Find the common ground and go from there. Don't get paralysis by analysis, throw up your arms in frustration and hit McDonald's. Cut out the sugar, don't eat anything in a package. Do it for a month. Go for a brisk walk each day. See what happens.
Health can sometimes be achieved with simple (not easy) tweaks in a daily routine. A few minutes of tissue work with something like a foam roller, a few activation drills, something to get you stronger and some body awareness. It may only take 5-10 minutes in your entire day. Sit at a desk all day? Buy and egg timer, every 15 minutes it goes off, stand up and try to touch the ceiling. Go back to work. See if that nagging back pain starts to go away.
Performance on the other hand is a commitment. It is carving out the time in your day, every day. Performance becomes a lifestyle. Asking your body to do something it has never done before, whether it's distance, speed or volume, requires you doing something you have never done before. This can be time consuming. Performance has a much higher cost.
Be clear on your goals, it will dictate the course of action that is required.