Poshsinglemum...it is certainly true that certain attitudes can affect what happens to us, especially in personal relationships. Often crap nasty people actively seek out people they feel they can abuse and bully, so if you have a sort of "victim" mentality or can't stand up for yourself you may become a target.
Self confidence is the key here (easier said than done). I found doing karate made my body language more positive and assertive.
Mentally I had a harder time and although I do a responsible job I often feel weighed down and inadequate, I don't think my colleagues would say that of me, I have a reputation for being a bit forthright!
When my mum was dying of cancer I had a terrible time and finally found help in reading "the Tibetan book of living and dying". I would consider myself a Christian but I find the Bhuddist faith much more practical in things like death and has a much better perspective than a lot of Christian teachings.
I also found Boethius's "Consolation of Philosophy" helpful, as it was written by a man awaiting execution and is an interestingly pragmatic view and contains that "why do bad things happen to good people?" chesnut.
My friend is a pagan but I find the rituals a bit off-putting. I think it is simply because I am so used to standard Christian church going, rather than them being intrinsically bad in any way.
I have also found meditation and yoga helpful, although very VERY hard to do as I have a very busy, worrying mind which finds it very hard to be still.
Also, bizarrely, I find radio 3 a great help, as it is so far beyond me sometimes I really have to concentrate to listen and understand!!!
I also took up gardening as the long term view you have to take when planting and growing things is very restful and satisfying, and takes only a little effort. It is also very Zen!
I have found all these things (over 10 years, I didn't change overnight) have helped me be more positive and calmer although I am still a bit of a worrier and do look at the downside rather a lot, but it no longer dominates my life.