Thread: I'm not sure where to begin

So I'm an out of shape and 45 years old. I have weight trained before but have never been consistent. I have a mild case of golfers elbow in my right elbow and have had some knee issues in the past. The only physical activity I do is skateboarding but I recently had to take a break from that because my left knee started giving me issues and I'm letting it heal.

My goal? I want to get into weight training (consistently) and I want to continue skateboarding, it is my passion. But I want to do both without getting injured. Or at least minimize my risk of getting injured.

Are there specific workouts or stretches I need to be doing to help prevent injury? Do core exercises help prevent injuries? Should I seek a physical therapist or personal trainer?

I'm ready to change my life around and become physically fit, continue skateboarding and do both injury free as possible but I just don't know where to begin.

Any advice?