The day you're in missionary with your girl, and tell her "Hold onto my neck/shoulders" pick her up off the bed and stand in the middle of the room holding her up is the day she will be yours no matter what happens after. They don't know it till it happens, but they all love to be manhandled like that, and only nikkas in shape can do that. Plus, if she leans back a bit the angle your dikk goes in her is rubbing the top of her wall.....
Do squats, deadlifts and snatches and you can hold her up for however long it takes and she will look at you like

for the rest of the month. Unless of course you like messing with them big bytches, then a hernia is in your future