I turned 40 in April. Last December I weighed 245 Lbs. and had 38% bodyfat. My bench max was <185, My squat max was around 225, I had never deadlifted or overhead pressed, and I couldn't do a real chin and could barely do a dip, and I got tired tying my shoes.
Today I weighed in at 208 with 24% body fat and benched 205 13 times on my money set. I deadlifted 375 to test for my 5-3-1 program several weeks ago and parallel squated 335. I am doing 5 sets of 10 dips for assitance work, the last set with a 40lbs DB between my legs. I did 31 chins this morning. I still feel like I could lose another 15 lbs and get alot stronger.
There are plenty of different ways to get into it. For me, I started lifting heavier weights on Sat. (push day - with squats) and Sun. (pull day - with deads) and did a total body circuit on Tuesdays and Thurs (10 deads with 135 lbs, pushups, assissted chins, dips, australian pull ups, dumbell press, curls, jump rope for 1 min., repeat 3 times, 30 sec rest between sets).
This started building strength and endurance and helped me cut weight. I am doing Wendler 5-3-1 now and waterskiing for HIIT. I eat as much chicken and grass-fed beef and vegetables as I can get my hands on during the week, have pizza night with the family on fridays, and load up on pancakes on Saturday and Sunday morning. I am still losing fat slowly, but I am much less concerned with this now. I a have a second piece of pie when I want to.
Also, I do some joint mobility work when I can, but I still need to do more of this. I personally think fish oil is the only required supplement, but I do take protein powder before and after my workouts and some creatine.
There is no reason not to get off your ass and get into the gym. The time is now and for the rest of your life. You won't regret it. Good luck.