I'm still in my newbie years
But I started training at the age of 33 myself, and when I looked at all the other martial arts and thought that "those are a young mans game, I can't possibly compete with their speed and stamina" Aikido was the one that stood out as the one where those abilities wasn't necessary.
Compared to others, we are young.
And about your background as a body builder, I think any Dojo should be thrilled to have you. We have a few really strong ones at our Dojo and they are great to train against, as unless you do a technique just right, it wont work.
And you yourself have likely been in situations (or can imagine) where your great strength would have hurt someone if you tried to subdue them. For you, Aikido will be a great tool you can use when you don't want to hurt anyone.