On that momentous day –April 10, 1998 – when the Belfast Agreement was finally signed, there was a sense of relief on the faces of the different politicians and government officials who had been part of the talks.
There was, however, also awareness that this was only the beginning and was by no means the end of the process.
It would be the foundation that would give the politicians the opportunity and the institutions to dramatically transform our society.
It was, however, not certain that we would ever actually reach agreement that would get the support of all sides.
After reading initial drafts, the Alliance negotiating team knew that we were still some way from achieving a final text.
I remember watching then Alliance leader John Alderdice holding a Press conference a few days before Good Friday, in which he said that Tony Blair better get on a plane to Northern Ireland – fast.
During the talks, we witnessed great statesmanship from the Taoiseach, Bertie Ahern, even to the extent of returning directly to the negotiations after his mother was laid to rest.
Whenever any senior figure arrived at Castle Buildings to enter the talks, they would be cornered by journalists trying to find out any little bit of information or indication of how it was going.
However, when the Taoiseach's car arrived, Eamonn Mallie stepped forward to say that they would not be asking any questions and to offer his condolences on behalf of the assembled media.
As the days ticked by and we got nearer to the deadline of midnight on the Thursday, some officials were getting more and more anxious as to whether or not we would be able to reach any sort of agreement.
I recall sitting in a BBC studio as I watched the clock reach that deadline.
After finishing my interview, I talked to a few people in person and also over the phone and I could tell that the mood of many people had dropped. As I drove back to Castle Buildings, we had to go past anti-agreement protesters.
If anything, their presence spurred us on.
In spite of this deadline passing and the memory of other failed attempts to reach agreement in the previous 30 years, there was still a feeling that this time was somehow different from before.
The draft that we had by that point was close to the final text and suggested that the different sides knew that we could not miss this opportunity.
There was a belief that we needed to keep everybody in the building on that Friday, otherwise people would give up on these talks and say that we might be able to try again in couple of years.
There was a sense that the time was now and that the circumstances that led up to April 1998 would disappear and might not be seen again. Eventually, after further exhaustive talks on Good Friday, agreement was reached.
I was due to be interviewed for a radio show just before 5pm when all the parties were due to gather for that famous scene when the agreement was announced.
I was able to announce to the radio station that we had the agreement before I had to cut short the interview to return for the unveiling of the agreement.
While undoubtedly much was achieved that day 15 years ago, much of its potential remains unfulfilled.
We were able to move our society forward, but we have missed many opportunities that the Belfast Agreement presented us with.
If we are to see the full benefits of the agreement, then we need to tackle to single biggest issue facing Northern Ireland: the delivery of a shared future for everyone.
As President Obama said two weeks ago: "There is urgent work still to be done – and there will be more tests to come."