I heard that space shuttles use up 60-70% of their fuel when taking off. Once it's out of the earth's atmosphere, it can cruise the rest of the way on the remaining 30% of the fuel tank.
Our lives are the same way. A new sport, business, or skill will take 70% of your energy just to get to its cruising altitude, then you can take your foot off the accelerator a bit.
Simple concept.
Big Problem: many people have the equation backwards. They want to ease into things. Go harder when the success comes. Or how about this one:  "Play for the long term results."
When was the last time you used all the gas in your tank for a day?
Time cannot be recovered, but energy is renewable. You sleep every night, so when you max out your energy output one day, you'll have a full tank the next day (assuming you eat well, drink water and all that good stuff). It costs you no money and you're gonna be sleeping anyway.
A space shuttle using 30% of its energy would never get into space. Most flying objects never get there either.
So if your aim is to go where most won't go, flip the average-person's equation.