My point, not very well expressed, is that "decline", in either the verb or noun form, exists as a concept. In one sense we begin to decline from the moment of birth. As an infant I was much more flexible than I was even by the age of three. At age three I fell down a flight of stairs and suffered no injuries, that would have been most assuredly present if it had happed when I was age 20. Yet, I lost that infantile flexibility as my body changed and moved to the next physical revision of me much in the same manner that I lost the unawareness of potential harm that gave me the ability to be completely relaxed while falling. The popular concept of "you've reached your peak; it's all downhill from here" is IMO an inadequate expression of the life cycle. Yet, it is the foundation of much of the thinking that age equals decline. It seems our dominate culture has an idealized image of what the perfect life condition/personal experience should be. While never explicitly defined or stated, it is expressed in much of our language, literature, art, thinking, etc. Hence, age, impairments, etc. are all seen as less than a full or idealized existence. Does this make this idealized image true? Of course not. The impact it has on your life, however, may depend on the extent to which you agree with its basic premises. Hence, for me going slower each year, as expressed by the OP, is not thought of as an issue of decline. The more powerful concept, from my view, is the ability to continue doing something one greatly enjoys for yet another year.