What I am really wanting to know is how happy people are who have made that decision to switch lifestyles, and how difficult it was in the beginning, and how they made it easier.
I think the first, hardest part, is to open up to another person about your desires; 'coming out' as it were. It requires a ton of trust. If you're past that, it gets easier in my experience.

To my mind, there is no line of embarkation, no split between vanilla and bdsm life. It's not some complete change that happens overnight. To make it easier, take it slowly and reasonably, just like you would with any developing relationship.

Understand that any serious, long term relationship is about compromise. You give and take, and adjust to another person because you can't imagine being without them. Vanilla still leaves a lot of wiggle room. If you've approached your boyfriend with "lets completely change our relationship," it's not surprising he's not interested. Start doing small, subservient things, that cross no boundaries. Call him "sir" from time to time. Kneel next to him when you watch TV. Offer to take over a chore, and do it in lingerie. After doing things like that, ask him how he liked it. If he complains about your serving him in lingerie, take him right to the morgue, 'cause the boy has no pulse. Otherwise, move from there, step by step, into heavier stuff: wear handcuffs to bed when you're frisky; it doesn't require he take any active part in your submission, but the next time his holding the key might not be much of a step. Ask him to bite your neck, or spank you. I suspect you'll find a point at which you can compromise. He might not ever whip you silly, and that may not be enough, but I honestly feel there is no truly caring partner that can't accomodate some of your wants and desires.

As for masters growing bored with slaves, that sounds like puppy crushes or too much fantasy fiction, and not enough reality. Yes, people can get bored with their sexual partners; that has nothing to do with bdsm. Personally, I think the innovation possible in bdsm can keep things a lot newer and exciting than vanilla, and thus is more often to stay intense, but I'm still awaiting the study. Seriously though, how dull can a partner get when they'll do nearly anything you tell them to? If you're slave isn't entertaining you sexually, it's because you're boring, not the slave. But I digress. I've been with my slave for 8 years now; most of my adult life, as I'm only 28, and we've been married for 6 of those. There are times we stagnate, but that's normal; we still have crazy mad passion on a regular basis.