Work out routine

Soo i want to start working out 1 day a week and i need a good exercise plan 😊i am not trying to lose weight i just feel like working out would prevent alot. Like i get really bad period cramps to the point where i am on the floor crying. Alot of it has to do with the fact that i dont exercise at all. So i figured that because i do not have to work Wednesdays i can work out for a few hours and then go home shower etc.

Ideas please ??