“I left and straight away said to my family and my friends that’s me done with playing at being a full-time manager,” he said.
“That was me done with it, it just wasn’t worth the sacrifice of a life outside the game.
“As soon as I left Billericay it was about driving my life in another direction. I still wanted to be involved in football, but being a full-time manager? Nah, not for me any more.”
Within a few days, his new business was built. The healthcare consultancy, thanks in part to the pandemic, is flourishing.
Problem is, so is the football.
Wealdstone and the Irishman together have worked wonders. The shock National League South champions are showing no fear, back dining at Non-League football’s top table for the first time in 32 years.
They’ve gobbled up most of what has been in front of them over the past month or so.
Defeat at Eastleigh on Tuesday night ended a five-match winning run which - remarkably - took them into second place.
Brennan, 40, is earning high praise and if he carries on like this, that dream of managing in the EFL could again be back on the agenda.
We didn’t have the heart to ask how this would affect business!
“I was in at work at 6.15am on Thursday and my lunchtime was spent watching a video of Sutton United!” he said.
“They’re good, by the way - they are going to come and have a real go at us on Saturday, make no mistake about that.
“I’m happy with balancing my life the way I am now. I’m busy, but I wouldn’t change that for the world.
“Family time is so important as well. I have two very little ones, aged three and five, and my son was run over last year. I’m taking him to another important appointment this afternoon, he’s getting there.
“Then it’s off to training and up again on Friday morning for work. That’s how it is.
“I’m not a full-time manager like I have been for a number of years before but it’s working for me. I’ve certainly got the buzz back for it since I joined Wealdstone.”
His team fell short on Tuesday night, but the players earned their little bit of slack.
The 2-0 defeat “wasn’t the end of the world” and on another day, the Stones would have taken something from it.
Brennan was calm, as he knows how much his part-timers have put in so far this term.
A slow start didn’t chance focus the former Grays, Stevenage and AFC Wimbledon midfielder, who knew a repair job wasn’t far away.
He couldn’t have prepared himself for back-to-back wins against Wrexham, Chesterfield, King’s Lynn Town, Altrincham, and FC Halifax Town.
From the bottom three to the top three in a blink of an eye, he knows things can go full circle again.
“The problem with this division is that after winning five games straight, you can easily then go and lose five games straight!” he warned.
“I can’t speak highly enough of these players, but I can’t say we’ve got a set target in mind.
“Well, I do have one - that’s to get to 50 points as quickly as possible. I don’t think a side has been relegated with 50 points for a long time, so that’s the first ambition.
“After that? Well, we’ll take it from there. We’re enjoying the ride right now, and so far it’s been quite a ride.
“It’s fantastic for the club to be in this position. Can we sustain it? Time will tell.
“But the way we play always gives us a chance to win games, even though we know there will be bad days and good days. We’ve wanted to be in this division for years but it is very demanding - every side is very, very capable.”
In particular Sutton, Matt Gray’s team have won the same amount of points, but have played two games less.
They have also conceded just five times and have won all their away matches - victories at Aldershot Town, Weymouth and Yeovil Town mean they are in fine fettle ahead of the trip to their old Isthmian League rivals.
Ahead of the live BT Sport game, Brennan has made a promise.
“It’s going to be better than the last TV game against Dagenham, I can guarantee that!” he joked.
“That was very tactical that day, both teams hadn’t started too well but Saturday should be different. It will be more entertaining, I’m sure.
“I’ve been so impressed with Sutton and what they have done so far this season, they’re a great club.
“They are expansive, they have bundles of pace and it’s going to be an end to end game, I’m certain of that.
“We’re a decent team. We have some good players but we have to be on it every week. We may have lost but I want to take the positives out of the performance on Tuesday night and we will.
“The players are working so hard. We may be a little naive at times, but it’s a learning process for each and every one of them.
“When we started back in the summer I asked the players ‘can we make an impact this season?’ and so far the answer is yes. I don’t know where it can take us, but we’re having fun and we’re enjoying it.
“It’s been fantastic, but we want to keep making an impression. We want to keep giving our fans who can’t currently get here something to be proud of.”
PICTURES BY WEALDSTONE FC