Dwight Eisenhower didn’t have “energy”, and Ronald Reagan liked his afternoon naps.
A little time for reflection, occasionally, does not hurt, either.
If you want to talk about “no energy”, how about the Current Occupant, who is so paralyzed at times he cannot make even a judgment call. And it has nothing at all to do with reflecting on various options - unless it is to take the absolute worst option on the table.
How many times did he vote Present as a senator? Time to golf!
It sticks in the memory of the listener much better than complicated policy issues.
For example if Christy had gained traction, Trump would have said something like "I know and like Chris, but I do worry about this health...you know, carrying around all that extra weight.
Trump is using the word "energy" to describe Carson's failure to clearly convey his ideas and plans with passion and determination.
Carson is no leader.