In the 1990s, I worked as an intern at a nonprofit in DC. Idealism rarely pays all the bills, especially not entry-level idealism, so I lifeguarded on nights and weekends.
Understand that for many hotels and apartment complexes, having a lifeguard on the premises is basically an insurance requirement. I got on the rolls at a pool services company & they knew I didn't have a car. I worked only at places that were close to Metro stops.
So the pool services company got me a weeknight gig at the Hyatt Regency Crystal City. This job was the GREATEST. All I had to do was fish children out of a pool occasionally AND I got a free room service meal every shift. For an intern living on $300/week, free dinner was huge.