Ian Craney`s double and a Sean McConville strike gave Stanley a seventh straight home win as Northampton were beaten 3-1.
Coleman`s men are a point behind seventh-placed Gillingham with a game in hand, but the boss said: "We know we have got to improve if we are to be successful.
"It is a long, hard slog now. We have a game on Tuesday and on Friday and it's possibly the biggest six days of my career. We are on the brink of something great. We have a marvellous opportunity and we do not want to throw it away."
He added: "Points-wise, it was a pleasing day. I think in the first half Northampton were the better team and yet they were 3-0 down. I thought we were better in the second half but ironically we lost that half 1-0.
"We were clinical in the first half but were wasteful in the second half. We usually come out of the blocks quickly but we didn't but have pinched the lead, that doesn't happen to us a lot. But the lads showed determination and finished the game strongly."