Fitness maven, drumming aficionado, wildly successful entrepreneur, committed philanthropist, mother of six — one might wonder if there’s anything Jennifer Maxwell can’t do. Maxwell, 56, launched her second business, JAMBAR, in September, 35 years after she and her late husband, world-class marathoner Brian Maxwell, made a name for themselves with the introduction of the PowerBar. As JAMBAR’s name recognition and marketplace presence grows, so does Maxwell’s giving. She has pledged to donate half of the company’s net profits to organizations that promote the causes she personally has embraced: Music and recreational sports, as well as other outdoor activities.