Breastfeeding and Pre-Workout

I want to get back into running and working out and have found it hard to get the energy and motivation to start. Before pregnancy I would sometimes take a pre-workout to help me in my workouts. Now 5 months postpartum, I'm having a hard time, I have no energy. I'm currently breastfeeding so I obviously don't take anything, but is there anything safe out there or a system I can work out?