The time to start thinking about retirement is always today, right now, right this second. The sooner you start saving and investing the more time your savings have to grow and become what you'll need to live on in retirement, but that's not the only reason it's better to start saving sooner.

During your lifespan there will always be a reason to put off saving for retirement. Whether it's paying off student loans, that you're not making as much money as you believe you will be later, that you're buying a home, remodeling the kitchen, having children, buying a car... and the list of constant possibilities goes on. Life, and it's expenses, aren't going to stop at some point and put up a sign that says ok, now it's time to save for retirement!

Most Americans aren't saving enough for retirement, it's a fact. The earlier you start putting some aside the easier it will be to make a habit of it. Certainly there may be times where you really won't be putting much aside at all, but every little bit counts. And those little bits that you save, if put into a 401k or IRA, will be invested and earn you returns over the years. The money you save when you're fifty will have a lot less time to be invested and earn you returns than the money you invest when you're 25 years old.

More than just the money part, you'll want to start imaging what it is you want to do during your retirement. Do you want to travel the world, play golf, take classes, learn to sew? A good thing to ask yourself is what do you not have time to do right now? These are things you can pursue in retirement. It's important to think about these things ahead of time, not only so you have some direction when the time comes, but so that you can play for any additional expenses you'll want to save for. What you'll be doing in retirement will have an effect on the amount you'll need for your yearly income, and the amount you'll need to save now overall.