In your thirties: establish the habit
Capture any employer match, increase contributions as income rises and balance retirement saving with debt and emergency reserves.
In your forties: test the trajectory
Estimate future income needs, review investment risk and account for education costs or caregiving without losing sight of retirement.
A plan is useful because it changes—not because every assumption stays right.
In your fifties: make the picture more concrete
Use catch-up contributions if appropriate, think through health coverage and compare possible retirement dates.
In your sixties: coordinate income
Evaluate Social Security timing, withdrawal order, taxes, Medicare and the cash reserve needed for near-term spending.