How do you actually scale without losing yourself or your team in the chaos?
In this conversation, Sivana Brewer sits down with Mara Castro, COO at Twentyeight Health and former Warby Parker trailblazer, to dissect what it takes to build, lead, and sustain high-performing teams in brutally demanding, mission-driven environments. Expect raw takes on leadership, the dangerous myth of “just do more,” and what it really means to earn trust as a COO.
If you’ve ever wondered why some leaders quietly burn out while others keep their team charging ahead, you cannot afford to miss this episode. Hear exclusive, battle-tested insights you won’t find in any COO playbook. Don’t settle for “what everyone does” and listen now before these lessons become your competitors’ next unfair advantage.
Sponsored by
Genius Network - An exclusive community for highly successful entrepreneurs, connecting you with top-tier leaders, strategic insights, and powerful relationships to help you grow your business faster and smarter.
Learn more: https://www.geniusnetwork.com/
Timestamped Highlights
00:22 – The unexpected journey from nonprofit roots to COO
02:37 – Why a career break fueled a powerhouse comeback
05:34 – The untold value of prior relationships for landing big roles
09:14 – Networking for introverts: How authentic connections really win
10:15 – The counterintuitive 90-day blueprint every new COO must follow
13:06 – The art of KPI clarity and not getting sucked into the weeds
17:50 – The hidden trap of too much complexity in health tech
33:23 – Why guiding, not micromanaging, unlocks leadership at scale
39:30 – The radical power of raising the white flag early
About the Guest
Mara Castro is the COO at Twentyeight Health, where she leads product, engineering, clinical operations, and pharmacy for a fast-scaling women’s telehealth platform. Previously, the first employee at Warby Parker, she helped build and scale one of the most celebrated brands in DTC history, before driving expansion at Evolve in hospitality tech. Her results-driven, human-focused approach makes her a standout leader in growth and transformation.
🔗 LinkedIn | Website
Mentioned Resources
About the Co-Host
Sivana Brewer is a Fractional COO for Remote Teams and former COO at Closers.io, where she helped scale the company to multiple eight figures and built over 500+ sales teams in just 2.5 years. She specializes in leadership development, remote operations, and systems that empower teams to grow sustainably.
🔗Connect with Sivana on LinkedIn
Important Links
The Second in Command Podcast is an original production hosted by Cameron Herold. Brought to you by COO Alliance. Production and editing by Podcast Your Brand.
Sponsored by
Genius Network - An exclusive community for highly successful entrepreneurs, connecting you with top-tier leaders, strategic insights, and powerful relationships to help you grow your business faster and smarter.
Learn more: https://www.geniusnetwork.com/
