You might think that designing the first computer would be a young man's game. Far from it. Charles Babbage started work on the Analytical Engine in 1833. He was 42 years old.
He kept working on designs for the Analytical Engine until 1846 when he was 55. He then stopped working on it and spent time on the Difference Engine No. 2 which was constructed by the Science Museum in the late 1980s.
Babbage returned to the Analytical Engine in the mid-1850s when he was 65 and kept working on it until his death in 1871 (aged 79).
The primary reason Babbage started so late on the Analytical Engine was that he was building up experience and knowledge prior to being 42 that led to its invention. He had started working on the Difference Engine No. 1 in 1822 (aged 31) and ideas for the Analytical Engine (such as the barrel based micro-programming and loops) came from trying to solve the problems associated with the Difference Engine.
That contrasts sharply with trends in the software industry where there's currently a cult of youth demanding that programmers be young and therefore relatively inexperienced. This comes about from the desire to deal with people knowledgeable about the absolute latest technologies, overlooking the fact that computer software undergoes macro shifts relatively infrequently (e.g. the rise of functional programming in the 1950s, structured programming in the 1970s, the dominance of object-oriented techniques in the early 1990s, ...).
Babbage's life points to the fact that experience can make an enormous difference and shouldn't be overlooked.