Motivated from Start to Finish

Money is no object. Okay, so maybe it is an object, and maybe it's an important one, but think about what's at stake here - your lifelong health - and compare that to other things you spend money on. Too many people dismiss a gym membership or a new set of weights because of the cost of the equipment or the monthly fees. But what other things are you allowing yourself to spend money on that aren't as important as your health? If you know you're going to go to the gym every day, then cut spending in other areas so you can make that happen. You're spending for your life now, not just for your immediate comfort. You could be adding years to your life with the money you spend on your fitness goals. Don't be afraid of spending too much.
But be realistic. Again, go to the forums online, find a group of dedicated people and ask their opinion. Do you really need that hat with the thing hanging off of it to learn how to play golf? Do you really need the fancy wrist-band or that camel-pack for your 2-mile runs? Spend your money wisely, but spend it when it's necessary to help you reach your goal.
An added bonus is that most people tend to put more energy into their investments. If you don't spend a dime on an endeavor, it's probably not going to be really high on your list of priorities. But by funneling a little of your hard-earned cash into your exercise program, you're more likely to pay attention to it and keep it up, so your investment will be worthwhile.
Get over the negative self-talk right now. Seriously, do it now. Go online and find articles, forum posts, and stories about people who have succeeded in your exercise program of choice. Save them in a giant Word document and keep it handy at all times. Find photographs that inspire you and hang them up everywhere. Designate one of your shirts or a pair of shoes as "lucky" and wear them whenever you need a boost.
Of course, none of this will be worth anything if you don't know when you need a boost. A lot of people don't even notice when they're talking down to themselves. It's become such a habit for so many people to be self-derogatory that they'll tear themselves a new one without even realizing the damage they're doing. Start noticing. Listen to feelings like "don't want to," and "can't." The second you spot those feelings, shoot them down. Imagine you're playing a video game, like Asteroids or something. Each negative thought is a giant space rock coming to crash down upon you and destroy your entire world. You are the only one who can save yourself! Shoot them down with brutal accuracy.
Those thoughts are not your friend and they will not help you. They want you to fail. The more you shoot them down, and the more you put a stop to them, the less frequently they will come around. Soon, your brain will no longer be plagued by unhappy thoughts and you will be free to explore this new part of space as freely as you like.