One runner at the Bank of America Chicago Marathon on Sunday proved that limitations don't define you.

Milan Petrović, 38, was born in Belgrade, Serbia, and has been blind since the age of 11. But that hasn't stopped him from competing as a high-level endurance athlete.

So far, he's competed in an Ironman triathlon in Romania, 30 half marathons, and now the Chicago Marathon.

Petrović finished the marathon with a time of 04:12:51.

His accomplishment is made possible with the help of his trusty guide, Dejan Ivankovic, who was by his side the whole way.

Petrović said his goal is to run all seven major marathons. After Sunday, he now has six left to go.