I really lack motivation when it comes to exercising. I do so well for a straight month and then I loose all my focus!
I have always had the same problem. I do great for a while, usually 4-6 weeks then life gets busy and I miss a day or two. Then when things get back to normal I find other reasons to not start back up. I often tell myself I will start again tomorrow.
What I have found that helps is having someone else hold me accountable. I will get someone who loves me (Mom, sister, friend) to have the responsibility of asking me about my workouts, or even do things together.
Many workouts have happened when I would rather do anything else, because someone was going to ask me about it tomorrow. It is the last price of motivation I use but when I really don't feel like working out it can tip the scales and get me doing something so I don't have to say I did nothing.