Posh went into the Final against the Sky Bet League 2 high-flyers after suffering five defeats in their last seven League 1 matches, but answered their critics and lifted the Trophy with goals from Josh McQuoid, Shaun Brisley and Britt Assombalonga.
With defeats to Rotherham United and Preston North End coming in their two most recent League 1 outings, Ferguson's side are now clinging onto a Play-Off place, sitting sixth, just a point ahead of Swindon Town, with eight games remaining.
"This [Trophy success] has come just at the right time for us. It could really energize us.
"The league form has obviously been the way it has, and we've got eight games now to make sure we stay sixth. The motivation is now to get back to Wembley.
"We've spoke about it all week, that once we've had a taste of this place [Wembley] - and it's a fantastic arena - we'll want to come back.
"The one thing we're good at is winning big games. I think this win stands us in good stead.
"It's going to be hard to sustain the Play-Offs but the one thing I did say to the players before the match is that teams don't like playing Peterborough in one-off games. They definitely don't, we've got a really good record.
"If we do get to the Play-Offs, and I'm confident we will, we have a good chance."
Despite the 3-1 scoreline, Peterborough were second-best for large parts of the game at Wembley against Chesterfield.
And Ferguson admitted that his side were fortunate, but took the chances that came their way.
"When we were 1-0 up it was very slow. We want to work the ball a lot quicker than we did.
"The big thing we spoke about was keeping the ball because we know Chesterfield are a good passing team. They're better than many teams we've faced this season.
"They'll be a League 1 team next season, hopefully we're not. They're an up-and-coming club. I would like to see them get promoted.
"Sometimes you just get the rub of the green and today I felt we got the rub of the green just at the right times.
"I felt we were clinical in the two goals we scored [in open play]. We had a little bit more composure, in terms of in front of goal.
"You need a wee bit of luck in finals and I think we got a bit today."
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