You're 23. Retiring with $3,000,000 at a 4% withdrawal rate would give you an annual "salary" of $120k. You make $80k right now, in order to save that much by 55, you would need to contribute ~30% of your gross income to retirement, assuming an 8% return, 5% annual salary increase and no employer match.
If you work to 65, the required contribution ratio goes down considerably.
The math is a little more complicated than in my example since I assumed all retirement savings are pre-tax but there's really no substitute for spending less than you earn.