U.S. marathoner Becca Pizzi is trying to become the first person to have twice completed the World Marathon Challenge — seven marathons in seven days on all seven continents.

That's already a lot of numbers. Here are more. (What's your excuse for not exercising? Yeah, we didn't think so.)

— All seven races are the classic marathon distance: 26.2 miles (42.2 kilometers)

— Fifty-five competitors will cross 16 time zones between the start in Antarctica and the finish in Miami

— Temperatures will fluctuate wildly: It'll be zero degrees Fahrenheit (minus 17 degrees Celsius) in Antarctica — maybe colder — and 80 degrees F (26 degrees C) the very next day in Cape Town, South Africa.

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All the to-ing and fro-ing might be as taxing as the running. Here's how the odyssey breaks down travel-wise — not counting getting to Cape Town or getting home from Miami:

— Day 1: Cape Town to Novo, Antarctica — 3,421 miles (5,506 kilometers) — flight time 8 hours

— Day 2: Novo, Antarctica to Cape Town — 3,421 miles (5,506 kilometers) — flight time 8 hours

— Day 3: Cape Town to Perth, Australia — 5,415 miles (8,715 kilometers) — flight time 11.5 hours

— Day 4: Perth to Dubai, United Arab Emirates — 4,732 miles (7,616 kilometers) — flight time 10 hours

— Day 5: Dubai to Lisbon, Portugal — 5,300 miles (8,530 kilometers) — flight time 11 hours

— Day 6: Lisbon to Cartagena, Colombia — 4,504 miles (7,248 kilometers) — flight time 9.5 hours

— Day 7: Cartagena to Miami — 1,101 miles (1,772 kilometers) — flight time 3 hours

— TOTAL DISTANCE TRAVELED: 27,894 miles (44,893 kilometers)

— TOTAL FLYING TIME: 61 hours

(SOURCE: www.travelmath.com )