Motivation can be hard to recover after such a time off. I seriously immersed myself into the track sprint side of cycling after cycling seriously for almost 10 years. It consumed most of my time. Life took a turn (fortunately not due to physical injusry like yourself) but it meant that a lot of my hard work got thrown out the window. I tried to get back to it, but I had lost so much that it was extremely hard to get going again. Then my daughter was growing and became active and successful at sports and I just didn't have the time to devote to it like I had now that I was chasing after her with training and competing. It's been going on for over 2 years now, but I've finally got some mojo back. I've actually taken up the sport of competitive woodchopping and that has given me some drive to get myself fit again and I am once again enjoying getting out and spending what time I can on the bike.
You got back on the bike, that is a good start. Don't try and go out and think you'll be able to ride like you used to. That factor has been a hard one for me to deal with after having been so fit and strong on the bike for so long. Find your reason to get fit and/or get on the bike and run with it. You will always find excuses unless you are properly committed to the reason