"Body building" is about body modification: unless your dead set on it I would highly recommend an effective strength training program. A book recommendation I'd toss at you is The Barbell Prescription: Strength Training for Life After 40.
I'm around your age, and still hover between intermediate and advanced in recognized strength standards. As I've gotten older, I've noticed a few things that are also noted in Mark Rippetoe's notorious book.
You'll need a longer warmup. I used to warmup for maybe 3 minutes before squatting an empty bar, and now it's more like 8 minutes.
The penalty for dumb mistakes is higher. You don't recover as fast, which really isn't a huge deal, but it's hard enough balancing recovery with an effective program let alone collecting injuries from bad form or overuse (like bicep curls and catching tendinits).
If you've ever read up on sarcopenia, it's the loss of muscle mass with age. Strength training is the most effective weapon in your arsenal to combat it, as this 2000 study notes:
The evidence presented suggests that [strength training] is an
effective intervention for improving strength, muscle mass and muscle
quality and delaying the onset of physical disability in the elderly.
I try to think that I can't stop getting older, but I can choose to be older and weak/fat or older and strong/fit.
Seriously though, don't go down the road of mirror muscles and bodybuilding if your goal is strength, fitness, and a healthy life. Squatting 300 pounds and deadlifting 400 will make you plenty jacked looking.