Gareth Thomas has revealed he is HIV positive, saying he wants to “break the stigma” around the condition.
The former Wales and British Lions rugby captain said he wanted to show how people with HIV are misrepresented as needing walking sticks and “close to dying”.
He has also spoken about the “shame” and “fear” of keeping his condition secret.
Thomas, 45, completed the Ironman triathlon in Tenby, Pembrokeshire after making the announcement – cheered on by crowds.
He finished the gruelling challenge in 12 hours and 18 minutes with high emotion along the way.
Gareth Thomas: HIV and Me will be shown on BBC One Wales on Wednesday 18 September at 21:00 BST, and on the BBC iPlayer.