I'm 25 and I've given 7 times so far. I've picked up pace in the past 1 yr. Now giving every 3 months regularly. And if it's apherisis, it gets even better. You can donate it after 3 days itself.
Belonging to a rare blood group (O -ve) and also being the universal blood group, it gladdens me like anything to donate blood.
For Indians, there is a site called bloodhelpers.com, an easy, very quick and hassle free way to contact donors. Register you and your family too. I'm registered in that site and I'm being contacted for donation every week. So much demand, yet so less supply.