"It can change very quickly and we need to keep winning to keep in touch - we are not far off first or second and if you keep winning three points makes a hell of a difference," he says.
"No game is easy and I am sure a lot of teams will slip up like we have been doing.
"We haven't had a run yet and maybe if do it will really push us ahead."
The key, he insists, is to keep the squad intact - including, of course, Jermain Defoe - and he adds:
"We can't afford to be letting any players go if we want to go up.
"I think we have got a squad that is good enough to get promotion."
Secondly, David believes that good fortune will be needed - something, he reckons, that has been deserting West Ham of late.
"We haven't had a lot of luck, definitely, and I have forgotten the amount of sendings off or late goals we have conceded.
"I am sure the things that have happened so far wouldn't happen in another season - and it is only half way through, so hopefully it will even out over the course of the season.
Looking at the win over Forest, David says:
"We played very well against a good side and deserved the win, I felt, and it was a good three points."
He was unlucky not to score just before being substituted and adds:
"I think it was more or less down the middle and it was an easy enough save for the keeper.
"In the last half hour there was a lot of space and unfortunately I wasn't there to capitalise on it.
"But I think we played really well, particularly in the first half.
"It was a big game for us; Forest are going through a tough period although they are a very good side and it was probably a game we had to win."
It went some way towards making up for the home defeat to Ipswich, and he adds:
"They are a good side and I think they played well but it is a strange one that we lost.
"We felt comfortable against them even though they are a good side and once we went 1-0 up I thought that was it.
"When they scored we thought 'oh no, another draw' and when they scored again it was disbelief.
"They probably did deserve to win and there is no doubt they are a good side."
Alan Pardew was delighted with the way he, Marlon Harewood, and Jermain Defoe all combined to help earn the win - necessitating in David having a more withdrawn role.
He is happy to sacrifice himself, as it were, for the greater good, and he says of his new position within the team:
"I am prepared to do it and it is different; there is not a lot else I can say!"