Smith was allowed to leave by Jon Brady at the end of last season and move closer to home with Kenny Jackett' s Leyton Orient.
Speaking in an interview with Sky Sports, Smith said: "I spoke to the manager Jon Brady at the end of the season and I said I felt like my time was a little bit hit-and-miss at Northampton; it had been stop-start with injuries and I couldn't get a run in the team.
"We had an honest conversation and I said I wanted to try and move on and get closer to home.
"Once I found out about Orient and especially when Kenny signed up to be the new manager, it was a perfect fit for me. He was a massive draw.
"I have played against a few of his teams in the past, including Portsmouth, and always seemed to do quite well, which he mentioned when I spoke to him.
"I went down and met him and I knew within five minutes that he would be the right manager for me.
"On the first or second day I was there, Neil Harris - my ex-manager at Millwall - came down to watch training. He saw me, we had a chat and just told me Kenny would be brilliant for me. That was exactly what I needed. It was music to my ears to speak to an old manager and get that reassurance from him."
Smith has netted 13 times in 24 games across all competitions for Orient this season and won the League Two Goal of the Month award for November following a stunning long-range volley against Sutton.
"I had been away a long time, had ups and downs along the way and never really settled," he added. "In the back of my mind, I thought that if I could get back down south of the river, I could really settle and kick on the football.
"To be on the number of goals that I am now is testament to myself and the hard work I've put in since I joined the club. I have got to praise the lads that I play with and the management team as well.
"I've not really worked specifically on my own game. I do feel that over the last few years I have probably listened too much to what I'm getting told to do and not played my own game. Here, the gaffer has wholeheartedly put his trust in me and trusts me to play my own game.
"I've pretty much played every minute of every game since the second game of the season and only come off once. It's probably the place I've felt most content, where I have most enjoyed my football and where I have been all round happy in my career."