All Strength is Not Equal
I'll soon be 71 years old and I like many men, and even women begin to think "I need to stay strong so I can maintain my lifestyle, remain upright and look good" soooo we join a gym to try and build muscle, assuming the larger our muscles the stronger we are, wrong :-o
We do get stronger as we gain muscle mass, however... your weight goes up as "the cube" of those dimensions, but your strength (ability to practically use those muscles) does not. This is why you'll never find a muscle bound rock climber, marathon runner, etc.
There is a remedy. If you lifting weights do many repetitions with low weight, not few with much weight because the first will offer strength without bulk (size) not strength with bulk. One is useful strength, the other is moot.
The information/guidance you'll receive from the majority of "trainers" is just plain wrong. Don't place your health, your life, in their hands. They may very well kill you.
I'm a physician who works like a health coach. If you desire to live a optimal life and need help I'm here for you.