Having had my third child in November, I’ve become a pro at fitting in workouts while tending to small children and work responsibilities. Here are my best tips on how to stay fit for new parents:Don’t fret if you can’t get to the gym everyday. Take advantage of any spare time you have to jump on your treadmill and run a mile or do a quick 15-minute high-intensity interval training workout while the kids nap.Invest in home exercise equipment. A treadmill or elliptical is great but also think outside the …