i m 50 yrs old my height is 180cm & my weight is 85 kgs,i m quiet healthy, i dont have any problems like high or low BP,daibetes etc im quiet fit & healthy i go for 1 hour walk daily so all in all im fine.since about a year i m having some erection problem,usually i have sex with my wife about twice a week,we have a very satisfying married & sex life,almost 99% she gets her orgasms,we have 3 kids,i m very well settled in life emotionally as well as financially,My problem is i get a very hard erection immediately as soon as we start foreplay,there is no problem initially but midway through foreplay i start loosing erection it start getting soft, & sometimes it becomes very impossible to penetrate, please help me.