Former US President Barack Obama and the late Nobel laureate Wangari Maathai plant a tree at Uhuru Park in 2006. [File, Standard]

Today, March 3, athletes of all ages and abilities gather in Nairobi's Karura Forest for the inaugural Wangari Maathai Marathon.

The race will include elite and recreational runners, as folks go through their paces at 5km, 10km, 21km, or 2km for children and the aged.

This will be special for me for three reasons, although I'm not a runner. First, March 3rd is Africa Environment Day and World Wildlife Day. It is also named, like the marathon, after my mother. My mom ("Prof" as she was fondly referred to) would have loved to join the runners, and plant trees with them and their supporters. She would have also appreciated the theme of the day, the "Power of One." "Each of us can make a difference and together we are a force" she often told me. And then she'd have got back to work!

The second reason is where the marathon takes place. A quarter century ago this past January, a few dozen people, including Prof, visited Karura Forest on the outskirts of Nairobi to plant trees. They were set upon by security guards, armed with clubs and whips. Chaos ensured, during which four MPs, two German environmentalists, and a number of journalists were injured, and my mother received a significant gash on the head. That same day, she made a formal complaint at the local police station, signing her name in the blood seeping from her wound.

Why would people planting trees be attacked in this manner, you might ask? After all, tree-planting (which is how Prof, the founder of the Green Belt Movement (GBM), became well known) had been a tradition in Kenya, going at least as far back as the 1920s. The GBM had already planted tens of millions of trees since it was founded in 1977. That number is now over 50 million.

The answer was greed. My mother and the others were bearing witness to threats to Karura from opportunistic land-grabbing and demonstrating what would be lost if it was cleared. Members of government at the time were handing out parcels of land in the forest to their cronies for luxury housing developments.

Prof and GBM had long campaigned against privatisation of public land, as well as encroachment on green spaces in Nairobi. For many citizens, parceling out of Karura was the last straw.

Although greed and lack of regulation around extraction of natural resources remain profound challenges to genuine sustainability and shared prosperity, whether in Kenya or elsewhere, what happened in Karura in 1999 was a watershed moment. The struggle reminded Kenyans of the need to protect their urban green spaces, and it began the long and occasionally halting journey to where the forest is today: home to pleasant walks, bike trails, and wildlife.

Urban green spaces are not only important for citizens' health and wellbeing, but they reduce air pollution, mitigate the heat island effect of the concrete jungle, conserve water and replenish rivers, and form carbon sinks. Karura is a living example of the importance of protecting what we have while restoring what's been lost.

The third reason is while we mourn the recent deaths of the young marathon champion Kelvin Kiptum and the legendary Henry Rono, we also need to pay tribute to the strength, discipline, and commitment to the skill they embodied - even in the face of personal adversity - and model it in ourselves.

Whether you're training to be one of the best distance runners, or you are planting trees, protecting forests, or nurturing democracy, you're conscious that the results of your work may be thwarted by outside forces or inner demons. Yet, step by step, seedling by seedling, fearless action by fearless action, day by day, you keep at it. Then you're rewarded with a moment of grace.

So, on this Wangari Maathai Day, whether you're in Karura for the Wangari Maathai Marathon or elsewhere, we can all acknowledge and learn from the patience, persistence and commitment of Kenya's champions, past and present, and as my mother loved to say, do the best we can to clothe the world in her green dress. In this, we're all in it for the Long Run.

-The writer is chair of the Wangari Maathai Foundation and Managing Director for Africa and Global Partnerships at World Resources Institute