For me, the biggest lesson of 2012 (so far) has been about dreams. Not so much motivating myself to pursue my own - I'm enjoying moving pretty much full speed ahead on that front of late - but on how others react to and support (or don't) my goals. It's an excellent lesson in staying on track and focused even when you're the only one who sees the vision actualized in the future.
In short (and in an effort to protect the poorly behaved), people in my life from whom I expected to find excitement or just caring about some of my new ventures have written the projects (and me?) off. I'll be honest: it stings. It feels like a denial of part of me as a person, and to an extent it directly affects how I feel about, and how much I trust, the people in my life.
The way I see it, it's really easy to protect the status quo. People in your life might have all kinds of reasons for doing so - fear that you'll leave them behind, shame at not pursuing their own dreams, desire for things to stay the same, inability to comprehend something outside of the norm - and they probably don't realize they're doing it. It doesn't mean you should let people go at your dreams unabated, but it does mean you can (and should) shrug it off and attribute it clearly (to yourself) as "their problem."
While I'm not a proponent of revenge, I do think the other way to respond is a good old-fashioned, I'll show you. I freely admit to silently logging those who give me disbelieving or, worse, placating looks (after I take a small - but rare - personal risk and tell them what I'm working on, no less!) and imagining how it will feel when they see my project come to fruition. There's no need for smugness or ego trips, but some healthy motivation can come from telling yourself you're going to make something happen that very few others believe is possible.
The other hidden benefit in all of this is that you'll be pleasantly surprised when someone shows up in your life who does care about your goals and believe you'll make them happen. Within the assembly line of haters, these folks stand out, and are very worth engaging as collaborators, mentors, or just key members of your network. I'll admit to being so surprised I got slightly choked up recently when, for the first time in a very long time, someone clearly communicated to me a strong belief in my future and unwavering support of my professional path. I won't take it for granted and I'll return the favor.
Returning the favor can be done preemptively, too. Whether it's a young person in your life, or someone who has denied a dream for a long time, think about what you'd want in their situation and say it or do it. It's karmic. And even if you never got back what you gave, wouldn't it still be sweet to be the person who moves another with your kindness? Yeah, it would.