New life, new me

Here I am at the start of 2013 with a whole new chapter of my life ahead of me. I am newly single and feel that it is a good time to make changes to better me all round. I have done the diet and excerise thing before & was successful. Sadly, and there is no excuse for it, but I tend to slack of when progress happens. Well, let's just say, I don't just fall of the wagon, I roll it, crash it & then burn it for good measure, lol. At 168cm and 65kilos, I don't think I am not bad, but at 37, I have noticed the tuck shop arms, the muffin top and the saggy bum and feel it is time to banish this for good! I aim to make a whole life style change, but oftern struggle with temptation, especially when I get home from work or on weekends. Does anyone have any pointers for me? Any tips would be greatly appreciated.