Sure, you can decide one day to lace up your running shoes and run. You can decide to join a gym, purchase a home program. Whatever. You can do those things. But, I can promise you that more than likely you won't find success. Not because you can't hack it. But because before you can attack the physical aspect of losing weight, you have to attack the mental aspect of losing weight.
Losing weight is, in my opinion, more mental than anything. It's a constant battle, everyday, to keep your head in the game and hold onto the ever fleeting motivation. I know this first hand. For me, going to the gym is easy. I just go. But, it's the mental part that gets me. Sure, I can walk into that gym, but if mentally I don't want to be there, it's going to show. I am not going to work as hard as I should. I may cut my workout short. I can't tell you how many times I have had an argument with myself in the gym. But, it's on those days, when walking up the stairs seems like a bad idea and going home would be easier, that I know that I need to be there.
But, you have to get to that point. You have to get to the point where you want to be in the gym or workout to the DVD more than you want to quit. You have to want it. Mentally you have to tell yourself that you are all in. Just as it's important to show up physically, you have to show up mentally. Everyday. No matter what.
No matter how hard you physically work, if you aren't in it mentally, it isn't happening. So, stop the negative self-talk. Tell yourself that you are worth it. When you're tired, tell yourself you aren't. And when you get to the point where you don't think you can do one more rep, do it. Then do another one.
You CAN do this.