kristen jarvis , 34 , is moving on from washington after seven years of acting as the first lady 's go-to gal and constant companion for nearly all her daily tasks .
all except some of the famously fit first lady 's more intensive workout regimes .
jarvis , who 's moving on to become the ford foundation president darren walker 's chief of staff , admits she did not share michelle 's love of d.c. workout craze solidcore .