The 29-year-old re-signed for Glasgow Warriors last week after negotiating his release from the French side, where he felt he had been frozed out by new coach Bernard Laporte.
Lamont, who has 26 caps, cited his lack of playing time for his decision to leave having spoken to Scotland coach Andy Robinson about his position following his return from New Zealand.
He said: "I spoke to him a short while after getting back from the World Cup and let him know my situation at Toulon.
"He told me I need to be playing rugby.
"It planted the seed that if I couldn't play at Toulon I had to see about getting loaned out or finding another club.
"I want to play in the Six Nations and I knew if I stayed at Toulon that was a definite no. I would not even be giving myself a chance.
He said: "I came back from the World Cup and I wasn't even close to getting selected.
"It was clear that there would have to be three or four injuries for them to put me into the 22.
"I thought it would be best to offer them the chance to release me and eventually they agreed."
After sanctioning his release, Toulon accused Lamont of refusing to integrate with the rest of the squad.
He said: "I was happy they let me go. I wasn't happy with what they said in the process of letting me go, which was completely untrue and unfair.
"It really surprised me that they came out and said that.
"They've got their own place to look after and they've got to look after the team and they've got an image to uphold.
"I suppose it doesn't look good when a senior player is leaving midway through the season.
"For me, it was just purely a rugby decision. I loved my team-mates and I got on with them really well - I just wasn't getting any game-time."
The full-back says he would welcome being thrown straight into Sunday's Heineken Cup clash against Montpellier despite a lack of recent match action.
He said: "I haven't played much rugby, I've played two games since the last game of last season with Toulon - against Italy and Georgia.
"That's not a lot of rugby in six or seven months but I've been training a hell of a lot in that time.
"These games will be a little bit like a pre-season for me but with a lot more pressure. If I'm selected, I'll be confident of performing and doing a good job."
Lamont had a previous spell with the Warriors between 2004 and 2007 before moving to Sale Sharks.
He added: "I'd like to think I've improved. I've put myself into some testing environments and I feel like I've grown up a lot.
"I do feel like I'm a much better player and I understand the game a lot better."