Justin has been adamant about athletics since he was 10 and found his current coach, Martin Rush at the same time. He joined the University of Bath to study Biomedical Sciences in 2021. Since then, he has represented GB twice and has consistently medalled at BUCS. Justin's 800m PB set in 2024 of 1:45.37 leaves him second all time Welsh. During this time Justin was also able to secure his first British senior medal at the 2024 UK Indoor Championships.

Justin had an incredible indoor season in 2025, winning his first British senior title and earning a place in the GB team for the European Indoor Championships where he went on to make the semi-finals. He also took victory in the Keely Klassic over 800m. Justin opened his season in style winning in both Belfast Bronze Continental Tour and Zagreb Gold Continental Tour He just missed out on securing his place at the World Athleltics Champtionships in Tokyo after finishing 4th place at the British Championships.