If you are either too quick or exhaustively never ending, this simple trick will help you ejaculate just in time.
Your prostate, the little helper up the ass, is the key to perfectly timed ejaculation. What you have to do is to harden or relax your anus muscles during intercourse.
If you want to prolong the act, relax the muscle and that should do it. Your penis will become a little less hard, meaning less friction, which in turn, means more time to the end.
If you want to come closer, tighten the muscle. This will put more pressure on the prostate and make the penis slightly more erect, leading in a speedy ejaculation.
In general, hard muscle means a sharper orgasm, while relaxed anus muscle result in a longer, overwhelming feeling.
Besides, regular muscle massage helps reduce risk of prostate problems in the future. Which make life a lot easier.