My workouts include aerobic exercise for a healthy cardiovascular system strength training to maintain muscle tone and bone density core strength exercise for a stable mid-section and stretching to maintain mobility.
At least for soccer players it comes down to a blend of two types of fitness - your base endurance which comes from longer distance running and your speed which comes from sprint-based workouts.
With both kids I started working out again at 16 days postpartum but I treated myself with kindness doing mild workouts because my fitness level was lower.
By learning about my body and making small subtle changes I find out what I enjoy and what is effective. I'm always finessing: adjusting my diet and my workouts. You have to figure out which exercises are fun and interesting and stimulate your brain - or else you'll never keep at them.