See a doctor, get prescription for Priligy (Dapoxetine), which is a short term SSRI (anti-depressant)
The thing is, unless you really don't last long enough but average like 5 min to cum, this will make you unable to cum for more than 30 minutes.
Some would love to last that long, but we are talking about non-stop, full thrusts for 30 minutes to finally shoot it out and it will get you exhausted.