When I first got a bike, I wanted to ride but was intimidated about certain things, like riding in traffic and not otherwise knowing where to ride. It was that intimidation and not my lack of motivation that held me back. I get the sense that you're experiencing the same things. So, my advice to you is to this:
Arm yourself with as much as you can to minimize the risks associated with riding in traffic. Practice looking behind you w/o swerving on a quiet street; use a mirror; wear high vis clothing; use a blinking tailight; avoid riding in rushhour traffic; know the rules of the road and how to use hand signals so that drivers know what you're doing; learn to ride in a steady, straight line; carry a cellphone and emergency information.
Practice riding on what are usual busier roads in the morning when traffic is light. That will hopefully give you a bit more confidence for when traffic is heavier.
Try to find a more experience friend to ride with.
Start riding on the trail if it'll get you out there (but me mindful that trails, especially multi-use trails, can be as nervewracking as the road.
Find other places to ride. Okay, this is harder than it seems, but I think this is what held me back the most when I started. I knew that there places to ride; I had friends who did long road rides with our local club, but I had no idea how to "access" that information and I was too nervous to join the club. Finally, I asked at one of the bike shops and they directed me to a marked route leaving from the shop that was 26 miles and went largely through neighborhoods and lightly traveled rural roads. So, I put aside my fears of riding alone and just started doing that route all the time. I had to drive to get there and it was sort of out of the way, but it gave me a place to start.
After many miles spent mostly alone on those roads, I finally got up the nerve to take part in a club ride. It was much less intimidating than I had built it up to be. From there, everything just got easier. I started to discover where I could ride and I met plenty of people to ride with. That was in September of 2006. Since then, I've ridden about 8,000 miles, including 5,200 last year in my first full year of riding. My point in sharing those numbers is that every great journey starts with one small step (or however that saying goes).
I'd encourage you to approach it with some baby steps of your own and give yourself time to gain some confidence. Celebrate each victory, no matter how small it may seem. Good luck and have fun!
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher