I'm 47, and in recent months have made a return to working out.
The workout that actually got me up and moving is Jari Love's original Get Ripped
. I started out using pairs of three and five pound weights (in various parts of the workout), and have since bought a cardio-type barbell so I can use a tad more weight than that, but on Jari's website, she mentions that absolute beginners can just use their own body weight in the workouts to begin with and work up to using barbells.
After a midwinter exercise hiatus, I picked back up with Get Ripped, using lighter weights, just to get back in the groove, and didn't have any particular difficulty (though I can tell I'd taken a break, my pushups aren't as good as they were, sigh).
Aside from that, one thing I've found very helpful is working on flexibility, and making sure to warm up and cool down thoroughly when I work out. My body clearly doesn't like it when I just jump into a workout and start something intense. Building up gradually, then easing off gradually, seems to be the way to go for me.
Lately, I've been using segments from Tamilee Webb's Total Stretch for Beginners
before I workout, just to limber up.
I also like Burr Leonard's 'Bar Method' workouts, they're intense but doable. There are a lot of barre type workouts (similar to Bar Method) available, so if one instructor doesn't float your boat, try another. :)
I guess what I'm trying to say is that it's important to figure out which styles of working out work for you. I dislike jumping around, and apparently I have NO talent for workouts on a step, so now that I've figured that out, it's easier to find workouts that I'll actually do.