The Spireites, who finished seventh, head to West Yorkshire with just two wins and one clean sheet from their last 10 games.
The Shaymen, meanwhile, secured fourth spot and have the best home record in the league this season.
But Cook says things can change quickly in football and that the Blues have an ‘equal chance’ as the other teams in the play-offs.
He explained: “We very much stuttered over the line, where other teams have run across the line, but we go into these play-offs now with a great chance.
“Football is a very, very funny game. There could be 20-30 points between the teams in second and seventh in some leagues but they go to a level starting blocks and that is what makes the play-off so unique.
"In these one-off games, you have got to turn up, you must turn up.
“One thing we know about our club is that our supporters will turn up. At the minute myself and the players have got to make them believe that we will turn up and that is the key message.
“In football confidence goes quickly but it also comes back very quickly. And you have got to do something to restore those confidence levels whether that is scoring a great goal or making a great save for a keeper.
“If things can go our way in the game, the confidence levels and the belief can come back in one night and that is what we are aiming to do at Halifax.
“We have not had a sequence that I have enjoyed at the minute but, as I say, my message is we go into the play-offs, in my opinion, with an equal chance as everybody else.”
Given Chesterfield’s poor form, they will go into the play-offs as underdogs but the Spireites could potentially use that to their advantage.
“I think as the jostling goes on, I think we would probably be the team that everyone in the play-offs wants to play if I am truthful because we actually look the weakest team going into it, but we can do something about that,” Cook added.
“For me, my biggest test at the minute is to try to put out a team that can win a game for us so I am not particularly bothered by the relevance of the opponent. I think all the opponents who finished above us are all very strong, well coached, well organised teams with good players.
“For us now it is about finding a way to win over in Halifax that will see our supporters leave that stadium elated and believe that we can go to Solihull and win a game of football again.”