Younger people really are faster and have more "energy". On a certain level this is just basic biophysics.
Particularly the kind of "energy" most immediately associated with the modern dev grind (i.e. to work long hours, and pick up toolkit X at the drop of a hat, etc). And you know, to just "believe" (in your company's mission; in whatever your stack is made out of this particular microsecond; in "Agile", or whatever).
None of which I'm knocking. A lot of times I feel I could still use that kind of energy.
But there are other kind of "energy" - e.g. the energy to resist learning too much about toolkit X (very likely to be obsoleted within 3 years). Or to get to wrapped up the latest architecture "debate". Or for that matter, in your company's "mission" (before it's at least halfway baked). Or, when people in your company start bragging about how many hours they "work", how no one really takes vacations and all... the energy to speak the intuitive and well-documented truth about where that strategy inevitably leads.
Both kinds of energy are needed. They aren't opposites; they're parts of a larger (necessary) whole.
The mistake lies in thinking that only one kind of energy is valid and sufficient to get your "mission" off the ground.