My sister has told me that I've changed

[wintersun]

I was having a moan about something to my sister earlier and she told me that I've changed from a positive, easy going , happy person to someone who is a bit of a moaner and a whinger.
She thinks dh is to blame and I've just realised that she is right.
I'm quite shocked by this realisation and don't want to be like this.
Dh is quite a negative person sometimes and I have had arguments in the past and told him not to try to bring me down with him. (He is not always like that and really is a lovely, caring person but prone to being a bit of a miserable old bugger)
How can I sort this out? I want to go back to being positive and happy.

I am probably the more negative person in our relationship and I get worse if DH argues with me about it. I'm always a lot more carefree about certain things when he encourages me as appose to commenting on my negativity e.g.

Me: "It's snowing, the roads will be a nightmare, I might have an accident blah blah blah."

DH: "Yeah but look how beautiful it is, don't go out in the car, sod the shopping - lets go sledging instead."

Maybe a silly example but if you are encouraging him to look on the positive side and just bypass his negative view then you should keep your own spirits up.