[1] Brought up in Baragoi, Samburu County, having lost his father early in life to cattle rustling, he was raised by his mother and later, grandmother.

[4] However, he was unable to compete as he failed to meet some of the Athletes Integrity Unit (AIU) doping requirements.

[5][6] Simiyu blamed Athletics Kenya for the debacle, claiming the federation did not inform him of the regulations before he signed up for the trials.

[8] He started the 2021 season with a victory after winning the elite-only San Silvestre Vallecana 10 km in Spain on 3 January.

[12] He was a silver medalist in the half marathon at the 2023 World Athletics Road Running Championships in Riga, Latvia in October 2023.