Exercise

Hey Ladies can y'all help me I'm going to start exercising Monday. I just wanted y'all to help me pick which one. OK so do I do 20 regular crunches or 45 seconds of regular cruches?

Or like

Squats: 20 squats or 45 seconds of squats.

Jumping jacks: 20 jumping jacks or 45 seconds of jumping jacks

Which one?