I just workout 3-5 times a week, mostly weightlifting and some cardio. Eating mostly healthy, save for the occasional junk once or twice a week.
I've tried P90X for 4 weeks. It was okay I just got really bored with it and have time to go to my gym. I'd rather just workout on my own and do what I like.
I agree that diet/nutrition is key to slimming down. I just ended my 1 month usage of Gaspari Nutrition Detonate. Wow! that stuff is great. Thermogenic properties, curbs the appetite well and not over stimulating. I'd recommend people to try that stuff out. However, I understand people like the structure and guidelines of a plan and challenge. I never weighed myself during my time using it, since I'm not concerned with losing weight but body fat. I noticed a decent reduction.
Losing weight or slimming down isn't really that difficult, I have pretty slow metabolism for how young I am. I like the Nike slogan, Just Do It! Once you get into the rythym of working out on a regular basis and start cutting out the junk food and alcohol it's easy.