The President, Mrs McAleese, on a two-day tour of Northern Ireland, has told an international conference in Belfast that if the peace process failed there would be "no square one to go back to".
Opening a conference of the Association of Directors of Social Services, Mrs McAleese said that, following the Belfast Agreement, there was tangible evidence that more people were supporting the peace process.
The President said: "There is tangible evidence that more and more people are taking personal responsibility for shaping a new society.
"It is essential that we hold on to and value that evidence for, when people forecast failure and our hearts sink, it is worth remain ding ourselves that there is no square one to go back to. We have all moved a long way indeed."
Referring to the problems facing marginalised people, Mrs McAleese said a just and lasting peace would be the greatest contribution to improving their lives.
"At the level of finances alone, one only has to consider the enormous financial cost of conflict and set it against, for example, the modest respite care aspirations of carers for Alzheimer's to see how skewed perspectives can get when we become obsessed with avoidable man-made conflicts instead of focusing on solving the many spontaneous and unavoidable crises and catastrophes life itself presents."
Such a change would, however, take time. "The change from a culture of conflict to a culture of consensus does not happen overnight or with the stroke of a pen.
She described political leadership as a "lonely place" and said she wished the politicians involved in next week's negotiations well. "In these difficult weeks, it falls to today's generation of politicians to find a common pathway through the chaos.
"Among them are the very people who have given us hope, whose determination, commitment, vision and courage have allowed us to hope for a new beginning. I wish them, each and every one, well as they carry all our futures on their shoulders over these delicate coming weeks," Mrs McAleese said.