Advice on how to stop worrying...

Does anyone out there have any advice for a FTM on how to control the worry I have that the pregnancy will end in a miscarriage???
Had a mc in April at 7 weeks and just got a new positive on Friday. We're really excited, and I have a much better feeling about this baby, but I can't stop thinking about the "what-if's." I'm normally such a logical and positive person that I'm a bit upset at myself for thinking so negatively about this experience that should be so exciting. 
Any advice is welcomed!! Thanks!