Here are few points from someone who has been training for 40 years.

46 or even 50 is not old.

Will you still see results training in a 80-90 percent of your max range? Yes , however that is not what I would recommend for every set.

It’s possible to see gains even in your 60’s. I am currently 61. The gains are small and do take longer and it can be completely frustrating, however there are gains.

The hardest part for most is just getting into the gym or doing’s some form of exercise each day.

Good article