First, instead of asking "why can't I do it" you should be asking "How CAN I do it" (check out Eric Thomas he's amazing)
Disclaimer: I have not completed my first deal yet, but I have talked to 27 potential sellers off my marketing in 3 weeks. The first one is coming...
I was until very recently also paralyzed by over analysis and fear. There's a couple key things that allowed me to stop reading and hoping and start doing.
1. I realized without a shadow of a doubt that if I can find a real deal, there's about a dozen guys and girls at my REIA that would help get it done. (50%>0%)
2. I also realized once and for all that I don't need to know everything about everything to START. I only needed to know enough about steps 1 and 2. I can always learn more while the phone's not ringing. Finding a deal is more important than everything else combined times ten. No deals = no money.
3. I made a plan (thank you Brian Tracy). I broke up the process in to the major components. Marketing,talking to sellers, property evaluation,contracts,selling the deal, etc and wrote down everything I'd need to do or learn
4. I started doing or learning the stuff on my plan
5. Action bred excitement which killed my fears.
6. Once it got real and I mailed my first 160 letters it was on. I haven't looked back. I may not have done a deal yet, but in my mind I AM a wholesaler (still have a 7:30-4 job) and when I'm not at work, all I want to do is work on my wholesaling business.
I wish you good luck. If you really want it I know you'll find a way.