Well there is some exercise that can strengthen the muscles of your organ, checkout on internet the way to perform this.
Moreover, stopping the practice of masturbation for 15 or 20 days will also increase your "enjoyment" time. Don't feel scared about pre-ejaculation, just calm down and enjoy your actions.
Premature ejaculations come from the initial emotional rush of penetraton. To extend your time in the "sweet spot", extend the time of foreplay 1/2 to 1 hour, that way the emotion has come and subsided somewhat and allows you to perform for longer periods.
