Hi, Welcome to HCM. Most of the times failure to get good erection is lack of sufficient sexual stimulus. Try fantasising about things which sexually stimulate you most, while engaging in sex. Certain medicines also reduce the sexual urge, such as those used for diabetese or hypertension control. If erectile dysfunction persists, consult an urologist and he should be able to advise you correctly. Viagra tab. has to be strictly taken under medical supervision as fatal incidents have been reported with it. Wish you all the best.