Most working-age people lack the time for voluntary work, a poll suggests.
Some 60% of 25 to 34-year-olds said they were too busy, rising to 66% among 35 to 44-year olds, and falling to 53% of those aged 45 to 54.
Just 29% of 1,001 people interviewed would consider helping to manage public transport services for free.
The BBC Radio 5 live poll also found most people preferred traditional voluntary activities such as working in a soup kitchen or coaching sports.
BBC home affairs editor Mark Easton said the figures presented "a real challenge to the Big Society", which involves people becoming more involved in all aspects of their communities.
Of those surveyed, 62% said they would consider working in a soup kitchen or homeless shelter and 51% said they would consider cleaning up parks.
Meanwhile, 47% revealed they would think about coaching a youth sports team.
Young people and the elderly were keener to volunteer than those in the middle age groups.
Some 71% of 18 to 24-year-olds said they would not be too busy, as did 61% of those aged 65 and over.
Sir Stuart Etherington, chief executive of the National Council of Voluntary Organisations, told BBC Radio 5 live Drive: "I think the encouraging findings are from the younger age group where a lot more people said they would volunteer."
But he added: "If this [volunteering] is seen as a substitute for services a way of transferring services I think it will ultimately fail".
Nick Hurd MP, minister for civil society, said: "Busy people will find time for things they care about particularly if they get a sense that it's normal... and that's part of the culture change we want to bring about."
The poll was conducted by ComRes from 13 to 15 August.