"I live alone, so I'm trying to force myself to get out and do other things," Barbara tells PEOPLE of her low-fi existence in a fifth-floor New York City walk-up apartment.
Luckily, Jenna, who lives outside the city, regularly comes to town and stays in hotels – where Barbara can get her TV fix. "She'll pack a bag and come stay with me," says Jenna. "We're in the room, and I'll be, 'Can't we read?' And she's like, 'Nope. Is there a Law & Order on?' "
Barbara also keeps it simple when she visits Jenna and her husband, Henry Hager – she takes the bus. "It's $10 and has Internet," she explains.
In a sitdown interview with the twins, 28 – daughters of former President George W. Bush – Barbara also talked about her own career. It may be less glamorous than Jenna's job, but Barbara is working quietly to improve people's lives.
After dabbling in design work (she still makes some of her own clothes on a sewing machine she got for her 12th birthday), Barbara co-founded Global Health Corps in 2008 after earning her humanities degree at Yale.
With a staff of only four, the New York-based nonprofit group grants fellowships to recent college graduates volunteering in health clinics in the U.S. and Africa.
For more of PEOPLE's exclusive at-home interview with the Bush daughters, pick up the new issue of PEOPLE, on newsstands Friday