Elite Endurance Athlete · Alberta, Canada

Cassandra
de Winter

Mother of three. Boston Marathon competitor. Course record holder. Proving that motherhood and elite athletics aren't mutually exclusive.

2:34
Marathon
1:12
Half Marathon
10:03
100km Ultra
Boston Marathon
Lost Soul Ultra finish
Mesa Half Marathon
Royal Victoria Marathon
Cassandra de Winter trail running in Alberta with the Lethbridge High Level Bridge in the background

Before anything else,
I'm a mom

Before anything else, I'm a mom to three young kids. My mornings begin early, balancing training with the familiar rhythm of little ones waking before the sun. In the midst of motherhood, I've found my way back to something that has always been part of who I am: movement, competition, and the drive to push my limits.

In 2025, after a few years focused on growing my family, I returned to sport through endurance racing. What started as a quiet comeback quickly turned into something much bigger. Running became a way to reconnect with myself, to rediscover strength, and to show my children what it looks like to chase something wholeheartedly.

My background in national-level rugby and strength sport gave me a foundation, but stepping into the endurance world has felt like starting fresh in the most humbling and exciting way. My journey is about balancing high-level training with motherhood, and inviting others—especially women and mothers—to believe that there is still space for their own ambitions.

The numbers

From 10K to 100K — every distance, every course record, built on early mornings and late-night feeds.

10 km
35:26
Half Marathon
1:12:54
Marathon
2:34:43
100 km Ultra
10:03:12

From comeback to course records

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Built on a lifetime of sport

Rugby

University of Lethbridge · National Team

  • Canadian U20 Women's National Team (2011)
  • Canada West All-Star — Back Three
  • Conference-leading try scorer (2 consecutive seasons)
  • Key contributor to Canada West Championship team
  • Rugby Alberta — Lead scorer & captain (multiple seasons)

Powerlifting

10+ Years in Fitness Industry

  • Overall Female Champion — Drug Free Competition (2018)
  • Squat: 292 lbs
  • Bench Press: 156 lbs
  • Deadlift: 370 lbs
  • Certified Personal Trainer & Coach

What's next

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3D-printed race keepsakes

Every race is a story written across a map—elevation gained, rivers crossed, a red line tracing the miles you earned. Mile-Mark Customs turns that line into something you can hold: hand-crafted 3D-printed topographic plaques of the courses you've run.

From the Lost Soul Ultra to the Grizzly Ultra to your local 50k, each hexagon captures the real terrain, the route in red, and the details that made the day yours—distance, year, finish time. A keepsake for the runner in your life, or the one staring back in the mirror.

Order on Instagram
Collection of Mile-Mark Customs 3D-printed hexagonal race course plaques
Hand holding a Grizzly Ultra 3D-printed topographic plaque with the race route in red
Cassandra and her partner holding a Sinister 50km Mile-Mark Customs plaque

@cassdewinter.runs

instagram.com/cassdewinter.runs

Let's connect

For sponsorships, partnerships, Mile-Mark Customs inquiries, or just to say hello.

Contact Cassandra