The link below is about businesses, but I see parallels with health and fitness:
A Million Little Cuts - Seth Godin
To summarize, businesses fail slowly from many small problems. They also can succeed quickly. The problem comes when they fail to fix the small problems and go for the broad strokes and expensive advertising campaigns without changing the way they do things. Have you ever tried to increase your exercise output while still eating the same types of unhealthy foods? How about drastically reducing your food intake but still expecting to have as much energy as you had before. Doesn't make a lot of sense, but it happens every day.
If your health isn't what it used to be, it may be because of several small problems that have added up over time. Think about how many calories an extra soda each day is after one year. What about five years? It might be because you are trying to exercise like an 18 year old and eat like one too. Your habits need to change with your age, because a 30 year old (or older) body doesn't work the same as a teenager's - just like your 10 year old car doesn't run like it did when it was new.
That was me before the Total Body Turnaround. Too many small problems conspiring to make it tough to do what I could do in my twenties.
The good news is the trend is reversible. You can get into great shape at just about any age. I've seen it happen, but rarely without a plan. You have to fix the small problems AND get a new plan. It's called a lifestyle change, and positive results can be rapid if you are consistent and committed.
Maybe these businesses and organizations in decline need to look at themselves as an organism in need of a lifestyle change....