Born and raised in Santa Cruz, California, Paul Schreiner was deeply influenced by his grandfather, a former surfer and surfboard craftsman. This early inspiration led Schreiner to embrace surfing at a young age, shaping his athletic foundation. His initial exposure to grappling occurred briefly during his senior year of high school, where he wrestled for several months. Schreiner completed his secondary education in New Zealand, where his athleticism drew attention from rugby scouts.

Schreiner began his Brazilian Jiu-Jitsu journey in 1996 at the academy of Claudio França in Santa Cruz. Despite significant setbacks—including multiple knee injuries and a severe staph infection—he demonstrated remarkable resilience. Under the mentorship of Claudio França and Garth Taylor, Schreiner progressed steadily through the ranks, ultimately earning his black belt in December 2007.

Alongside Garth Taylor, Schreiner co-founded Kaijin Academy in Santa Cruz, California, establishing a respected training environment. His instructional reach expanded further when he began teaching at the renowned American Kickboxing Academy (AKA), collaborating closely with Dave Camarillo. Schreiner also pioneered a unique Brazilian Jiu-Jitsu program at Apple Inc.'s headquarters in Cupertino, introducing grappling to the tech community.

In 2010, Schreiner joined the instructional team at Marcelo Garcia Academy in New York City, quickly becoming a cornerstone of the academy's coaching staff. He played a pivotal role in developing the academy's acclaimed "brown belt dream team," mentoring future world champions such as Bernardo Faria and Dominyka Obelenyte. When Marcelo Garcia stepped back from teaching around 2020, Schreiner upheld the academy's high standards, becoming synonymous with its reputation for detailed, conceptual instruction.

Widely respected for his technical precision, Schreiner excels at fundamental techniques, particularly pressure passing, posture, and guard balance. His suffocating top pressure has earned praise from elite competitors, including Bernardo Faria, who credits Schreiner's instruction as instrumental to his competitive success. Schreiner emphasizes conceptual understanding and adaptability, teaching students to respond dynamically rather than relying solely on memorized sequences.

Throughout his career, Schreiner has mentored numerous high-level athletes, including Bernardo Faria, Dominyka Obelenyte, Dillon Danis, Mansher Khera, Matheus Diniz, and Jonathan Satava. He has played a significant role in preparing competitors for major tournaments, including the IBJJF World Championships and ADCC 2015. Schreiner's quiet yet profound influence has shaped the careers of multiple world champions.

In mid-2023, Schreiner opened Frogtown Jiu-Jitsu in Los Angeles, marking a significant new chapter in his career. The academy emphasizes technical proficiency, adaptability, creativity, and meaningful connections in training. Maintaining affiliation with the Marcelo Garcia Association, Frogtown Jiu-Jitsu benefits from a proven curriculum and extensive network, with Marcelo Garcia himself conducting seminars at the academy. Early reviews highlight Frogtown's inclusive environment and Schreiner's personalized mentorship approach.

Schreiner advocates a philosophy of intelligent training aimed at longevity, encapsulated in his mantra "tap early, train tomorrow." With over two decades in Brazilian Jiu-Jitsu, he remains a dedicated student, regularly attending seminars, studying new instructionals, and actively participating in classes at other academies. Known for his approachable and ego-free personality, Schreiner fosters genuine connections with his students, emphasizing incremental progress, enjoyment, and sustainable growth in training.