So i have to disagree, I was given very much the same information as Yo had been given early in my career. I am now close to 50 and (still 4 years but close enough) and my job opportunities are more then they where over the last 15 years. And i have the ability to move into different areas, with my creative thinking and ability to strategically look at innovative options and solutions. And this goes beyond developing physical products. By sixty i hope that i am retired and have gone back to consulting and sharing my knowledge of design and development at a high level to help companies speed up their leanings and reduce their mistakes. (or i could be in a retirement home)… I have also worked with some designers who are at 60 plus and they are at the top of their career and extremely respect by the companies that retain the them. In the end we all have different experiences and mental models which shape our perception.