Brett Halliwell

Coach

Watching Optimal Endurance grow over the past two years has been incredibly rewarding—not just in numbers, but in the community we've built.
COACHING SERVICES

Bio

Endurance sport has been a big part of my life since I was 10, when I first stepped onto a running track. I started with 800m races, moving up to the 5000m, alongside cross country and road races up to the half marathon. I gave triathlon a go at Tri Stars level around the same time, but I didn’t stick to it back then—I stepped away after just one season.

Fast forward to 2016, and I found myself back in the sport, this time at 21 and racing sprint distance triathlons. That year, I competed at the World Age Group Championships in Chicago. I progressed through different race distances, and in 2019 I earned my professional license. I was fortunate to race as a pro until 2023. This helped me gain insights into how top athletes approach both training and racing. I had the privilege of training alongside some of the best performers in the world.

Since stepping back from racing, I’ve been able to focus on coaching. It’s been incredibly rewarding to channel what I’ve learned into supporting my athletes, helping them train smarter, build confidence, and achieve their goals.

Future Plans

Coaching has been a passion of mine since finishing college, and my goal has always been to support as many athletes as I can in a sustainable and meaningful way. Watching Optimal Endurance grow over the past two years has been incredibly rewarding—not just in numbers, but in the community we've built. We're more than just a coaching service; we're a supportive network where every athlete feels backed, connected, and empowered to reach their potential.
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My Goals


Ready to Join?
Helping athletes go from zero swim/bike background to completing Ironman Tenby in under a year
Supporting athletes in achieving PBs across all distances and disciplines
Tailoring training to each athlete’s unique needs and lifestyle
Committing to ongoing learning so I can keep giving my best to those I coach

Interested?

Coaching Rates

We offer two monthly coaching rates: triathlon training for athletes preparing across all three disciplines, and single-sport coaching for those focused on just running, cycling, or swimming.

Triathlon / Multi

Triathlon training builds endurance, strength, and skill across swim, bike, and run.
£175
monthly
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Single Sport

Focus your training on running, cycling, or swimming to build strength, endurance, and skill.
£125
monthly
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TESTIMONIALS

SAM

Long Distance Triathlete
"Brett has been coaching me for around 1 year, building my swim, bike and run in preparation for 1/2 distance triathlons and more recently marathons. 

The improvements I’ve seen have surpassed all expectations especially running. 

Brett has managed to make my training work around my shift work and has kept the sessions varied and specific for me"

LLOYD

Long Distance Triathlete
"The Optimal Endurance team provide the best level of coaching and care related to any level of ability or experience. 

Brett was an excellent coach during my training period leading up to race day and without his knowledge, experience and support my Ironman experience would not have been as great as it was. 

Thank you Brett and the rest of the team!"

ALED

Long Distance Triathlete
'Brett goes beyond simply writing training plans – he takes the time to explain the reasoning behind each session, helping you train with real purpose and clarity.

Brett goes the extra mile often coming to the big races in person. This makes a real difference. His presence on course – offering advice, encouragement, and support. My only regret is not joining sooner."
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