Juan Estrella, a Kellenberg math teacher and track coach, is the only person to win the Long Island Marathon three straight years. Here are some of his pointers for first-time marathoners this Sunday.

Have a strategy for first 20 miles.

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Estrella said he mistakenly ran his first marathon based on how he felt, which he believes cost him much-needed energy for the end of the race. Know the type of pace you want to run, he said, and stick to it.

Accept that you’ll feel pain.

“Every marathon I’ve run I’ve always come to a point where I say, ‘What I am doing out here? Why am I putting my body through this?’” Being prepared for those thoughts will help you fight through it, he said.

Enjoy the experience.

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Know the spots along the course where family and friends will watch from, so you can anticipate seeing them. “If you’re a runner it’s one of those races you have to do,” he said. “If you haven’t done it, you haven’t completed your journey as a runner.”