I'm not so sure that you need to surround yourself with positive people. My thoughts lean somewhat counterpoint. I think that you should make a very concerted effort to eliminate negative people from your life. Easier said than done, yes, and frequently with some regrets of benefits lost, but the times I've made that leap, and taken action, the positive benefits to me and sometimes mine, has been more than worth it.
Just this week I had a conversation with a young woman, relating my story of one very strong relationship I finally ended when I realized the daily, constant, negative impact on my life, and loved one's lives, was simply not worth maintaining. It was hard to sever, and had it's downsides, and I still think about it to this day, but with no regret. I am convinced that it's one of the best things I've ever done, even though I fervently wish I hadn't had to do it. It's a life lesson most parents want to pass along to their kids - the tried and true "guilt by association" lesson - be careful who you chose to be your friends.
It gets complicated when it's a family member that's "negative," since you don't chose them, but I'm a firm believer in biologic connection not being a "free pass" to abuse or down trod.
Just my two cents.