It is very difficult to save $1,000,000.
OTOH it is not difficult to save 15%, invest the money and end up with well over that number.
Not if you start young and understand how compound interest grows your money.
Smart investments in financially solid companies that pay dividends which are then used to fuel your retirement fund's growth also helps.
The trick is START YOUNG.
Both my teenage son's have put everything they've made into their own 401k's since each was 12 years old. They had to save up the first $1500 to open the account, mom and dad made up the difference ($1,000) so they could open up a starter 401k of $2,500.
Oldest son's 401k went from $2,500 at opening account balance to just over $6500 as of his last balance. That's more than doubling in 5 short years. Proves the sooner you start, the faster your money starts doubling.