For Coupar, public service is a family legacy. His father, Charles (Charlie) Coupar, a renowned horticulturist who spent over four decades with the Vancouver Park Board, served as the inaugural director of the Bloedel Conservatory. It was through his father's work that Coupar's commitment to the city's green spaces first took root – and at age 13, standing beside his father at the Conservatory's grand opening, that commitment was cemented for good.

This commitment was put to the test in 2009 when the Park Board marked the Bloedel Conservatory for closure. Determined to protect his father's legacy, Coupar spearheaded the defense campaign by co-founding the Friends of the Bloedel Association. The successful grassroots initiative not only saved the facility but also established a partnership that boosted annual attendance and earned him the City of Vancouver Heritage Award of Honour in 2013.

During his time at the Park Board, including two years as chair, Coupar established himself as a defender of public assets, challenging administrative shifts toward developer-centric policies. His tenure was marked by a few major successes: he secured vital restoration funding for the Bloedel Conservatory, oversaw marine upgrades at Vanier Park, and facilitated the development of the Killarney Seniors Centre and False Creek Dragon Boat facility. Alongside this record of achievement in public office, Coupar built a career in the private sector, most recently as President of a carbon-neutral transportation company.