Let me tell you the story of Shane Dolan. I met him two decades ago, when I was in Ethiopia for Four Corners, filming The Forgotten Famine.

Shane was an aid worker. Not the kind who hands out food at emergency relief centres, but the kind who works for the long term.

His work was all about building wells; in that parched country near the Horn of Africa, nothing is more valuable than water.

Without a well, the women of the village have to walk miles carrying huge jerry cans of the precious fluid from the nearest source.

One well can transform the life of a village.

But Shane’s work with the charity then known as Community Aid Abroad (now merged into Oxfam), was not just in digging the wells themselves.

His mission was to go a step beyond direct aid of that kind, and teach Ethiopians how to build their own wells.

It’s the aid philosophy that says, “Give a man a fish and he’ll eat for a day: teach him to fish and he and his family can eat every day”.

It was almost unimaginably difficult work. The philosophy was to use local materials and local technology to build the wells.

It wasn’t as if there was much choice about that; there was no electricity, very little access to fuel, and very few vehicles.

Even when there was petrol, people like Shane had to be able to strip down their own truck engines if anything went wrong, on top of their central tasks – finding and shaping local stone to dig and reinforce the shallow wells appropriate to the terrain, and teaching untrained workers to do the same.

And remember, all of this was in the middle of a war zone, with the ever-present threat of attack from the Ethiopian Air Force.

For years, I held the image of Shane Dolan in my mind as one sort of ideal of what an Australian abroad might be: tough, practical, but caring, and able to relate to all kinds of people in any situation.

But Shane Dolan had been doing it hard, as I found out when he rang me last year.

He had come back to Australia in 1992, depressed and shattered, feeling perhaps defeated by the sheer enormity of the problems; this man, who I had depicted in a film as achieving so much, felt himself a failure.

Call it a breakdown, call it post-traumatic stress disorder; whatever it was, Shane’s life and career fell to pieces for a while.

But that’s not how the story ends.

Yesterday I opened a letter from Shane Dolan, telling me that he’d been back to Ethiopia: I’ll let him tell the tale in his own words.

“The trip back … was absolutely incredible. The program we started some 22 years ago, where we trained 19 shallow wells technicians, has expanded to 63 technicians and provided 1.2 million Tigrayans in remote rural areas with clean drinking water. It has been a huge success and recognised throughout Ethiopia and Africa as a model for community development and self determination.”

“My colleague Peter and I were treated like long-lost sons and war heroes. We had no idea as to the success of the project or in fact whether people would even remember us. Everywhere we went people were able to recount stories of our time there. They couldn’t understand why all that time ago we came halfway around the world into their war-zone and famine situation for over a three-year period.

“There were endless hugs and tears as we were reunited with old friends and colleagues. We were the guests of honour at many celebrations. We dined with the President of Tigray.”

Shane’s letter moved me deeply. Depression works in part by distorting your view of yourself in relation to others, so that you lose sight of how greatly you are valued by others. For Shane Dolan, going back worked literally like a cure.

“For many years”, he writes, “I felt like such a failure … Returning after 17 years and witnessing what has been achieved and the respect from the people has allowed me finally to validate my experience and start the process of rebuilding my self-esteem. So after crying a river of tears, and many reunions and hugs, the healing process has begun. It feels like I have been holding my breath all these years.”

Now that he can (metaphorically) breathe, Shane Dolan is working for Ethiopia again. Having identified gaps in the supply of quality construction equipment, he’s organising a shipment, financed by the Australian NGO Planet Wheeler Foundation.

And he’s trying to put together a documentary about his experience of going back, using 23 hours of footage that he shot on the trip. I, for one, look forward to seeing it.

Mark Colvin is the presenter of ABC Radio’s current affairs program PM.