David Cameron has revealed his first new role after quitting political life will be to lead an expansion of the National Citizen Service for teenagers.
The ex-PM said the scheme, which he set up during his time in office, was "the Big Society in action".
The NCS aims to prepare teenagers for work through team-building activities and community projects.
Mr Cameron will be chairman of NCS Patrons, aiming to make the course "a normal part of growing up".
Having resigned as prime minister in the aftermath of the EU referendum, Mr Cameron also quit his Parliamentary seat last month.
In an article he has written for the Daily Telegraph, he said setting up the NCS was one of his proudest achievements, with more than 275,000 having taken part.
He said it was "building bridges across social divides", creating lifelong friendships between teenagers and "building the soft skills, the resilience, the self-confidence and the creativity that can help them get on in life".
He said his new role would involve "bringing together a senior cross-party and cross-sector group of patrons and ambassadors who can help NCS to reach more youngsters".
"By bringing together expertise from every part of society we can embed NCS in our national fabric," he said, adding that he hoped to "make it a reality for generations to come".
The former PM said he was "delighted" his successor, Theresa May, was pressing ahead with a National Citizen Service Bill, which would put the NCS on a permanent legal footing.
"But making NCS a rite of passage requires more than political leadership," he added.
"It requires leadership from every part of society."