> How do you do that?
For the last decade, 10-15% average annual return would have required keeping 70-90% of the funds invested in Nasdaq-100[1].
Also, Vanguard 500 Index Fund (VFIAX) currently has a 10-year average of 13.52%[2].
The general advice is not to keep more than (110 - your_age)% of your retirement portfolio in these high risk / high rewards funds.
Therefore, it's entirely possible to receive 10-15% annual returns until you turn 40, but as the period of time until retirement shorters, it becomes too risky.
In other words, what is a "medium-risk" at 35, can be a "high-risk" at 55, because one might not have enough time to recover from an economic crisis at an older age.
[1] https://www.nasdaq.com/articles/when-performance-matters%3A-...
[2] https://investor.vanguard.com/mutual-funds/profile/overview/...