Bladder stones are usually associated with urinary stasis but can form in healthy individuals without evidence of anatomic defects, strictures, infections, or foreign bodies.
In adults, the most common type of vesical stone (seen in more than 50% of cases) is composed of uric acid while in children, stones are composed mainly of ammonium acid urate, calcium oxalate, or an impure mixture of ammonium acid urate and calcium oxalate with calcium phosphate.
Vesical calculi may be single or multiple, especially in the presence of bladder diverticula, and can be small or large enough to occupy the entire bladder. They range from soft to extremely hard, with surfaces ranging from smooth and faceted to jagged and speculated.
The most important requirement to preventing bladder stones is that you increase your water intake - start drinking large quantities of water during the day. This will of course increase the frequency of urination, thus increasing the probability of flushing out the stones when you pass urine.