How can I make my hair grow stronger?

I have very silky and thin hair about shoulder length.I want to grow them stronger and longer.
please help me.

Your hair will be healthier (and able to grow stronger and longer) if you are eating a well-balanced, nutritious diet. Foods full of vitamins and minerals will help your entire body be healthier, including your hair. As well, try not to pull it into ponytails, as the rubber band can break your hair. Use a soft hairbrush, wash regularly, and try not to 'fry' it too much with hairdryers, curlers, perms, dyes, etc. Working out on a regular basis will also do a lot of good for your skin and hair. And, drink plenty of water, mineral water is always good, but plain water does the job fine. My hair was at its healthiest when I drank only mineral water, bicycled every day, and ate a well-balanced diet. Best of luck.