Walt was absolutely not lying. Throughout the show he's had many times where he could have backed out of the business, but kept going because he likes it. He has a huge ego, and for the first time he's respected (Jesse actually sees the art in what he does, which is something he is unable to show his students in his chemistry class who could care less about his passionate lectures.) And as Heisenberg he's powerful.
But if you need proof you just need to look at "Over" from Episode 2. In that episode, Walt has just found out his cancer is in remission. He's also just produced a huge amount of meth that he can now sell and pay any bills he may have (I believe that's what he eventually sells to Gus for half a million dollars.) Tuco's long gone, and at this point Walt has an easy exit from the business. He's accomplished his goal of paying for his treatment and helping his family. Nobody at this point is pulling him back in.
But Walt is unable to satisfy himself around the house, and when he sees the kid buying the ingredients for meth at the store, he goes up to him and says "Stay out of my territory." That is pure ego from Walt. He is proud of the blue meth, he's proud of his work, and he's proud of Heisenberg.
I think that was the moment Walt stopped providing for his family, and started providing for himself. Remember even from Season 1 he was getting much more sexual as a result of getting off of the excitement, and when drunk Walt often reverts to his Heisenberg persona. This is a man who was never respected, and finally is proving he's great and powerful. In the end, he tore apart his family with his work, which is contradictory to what he claims was his cause, but he needed to tell HIMSELF that he was doing it for his family. In the end, he finally admits to Skyler and himself that he was doing it for himself the whole time (Or in my opinion, at least since the episode "Over")