Babysitter Needed

Looking for a babysitter for a 15-month-old. We're looking for someone long-term (this is not a summer job!). We'd like to start with 1 p.m. to 3 p.m. twice a week (whichever days work best for you, and maybe occasionally 3 times a week), but soon, when baby needs to transition from 2 to 1 nap a day, we'll need to move the hours to something earlier in the morning (9:30 to 11:30 or so). Our baby is very active, running everywhere and we need someone who feels fit enough to prevent him from falling and hitting the walls! We live in Bryn Mawr, near Garrett hill station.