Here's exactly what to do, starting today.
Days 1–7 (This Week):
Get your free credit report from annualcreditreport.com. You're allowed one free report per year from each bureau (Equifax, Experian, TransUnion). Get all three. Read through them. Write down every account and when it was opened. You're looking for old accounts you might have forgotten about. Don't close anything yet. Just read.
Days 8–14:
For each account you found, decide: keep it open or close it? The rule: if it's old (5+ years) and has a positive history (no late payments), keep it open forever. Don't close it. If it's new (less than 2 years) or has a negative history (collections, charge-off), you can consider closing it after the negative item falls off your report (7 years from first delinquency).
List all accounts you're keeping. Find one card per account and use it once (buy gas, pay a bill, order something online). Pay it off immediately. This keeps the account active.
Days 15–30:
If you have family members with older accounts and good payment history, ask if you can be added as an authorized user. This is free for them and costs you nothing. Their old account gets added to your credit file, boosting your average age. This is the fastest way to improve age if you don't have much history yourself.
Also: make a note of when you last opened a credit account. Calculate how long until you can open the next one (6–12 months from the last opening). Put a reminder in your phone. Don't apply for credit just because you got approved. Apply only when you have a real need (mortgage, car, debt consolidation).
Days 31–60:
Make sure your old accounts are active. Use one card every 30 days (doesn't matter what—just pay immediately). Set reminders in your phone if you tend to forget about accounts.
Review your credit report again. Check for any errors (wrong account opening dates, accounts that should be closed but show as open). If you find errors, dispute them through annualcreditreport.com or directly with the credit bureau. The Fair Credit Reporting Act (FCRA) requires bureaus to correct inaccurate information within 30 days.
Days 61–90:
Check your credit score. Use a free tool (Credit Karma, Discover Credit Scorecard, your bank's credit score tool). Write down your score. If you took action to keep old accounts open and not open new ones, your score should hold steady or improve slightly over these 90 days. The real improvement comes over months 4–12 as old accounts age and new accounts improve in age.
Make a commitment: no new credit applications for the next 6 months unless absolutely necessary (home or car purchase). Each month that passes without a new application helps your average age.
Schedule a reminder in your phone to check this plan again in 6 months. By then, any new accounts will be 6 months older, and your average age will have recovered significantly.