The first week she walked 1 mile, 6 days a week for a total of 1*6 = <<1*6=6>>6 miles
The second week she walked 2 miles, 6 days a week for a total of 2*6 = <<2*6=12>>12 miles
The third week she walked 3 miles, 6 days a week for a total of 3*6 = <<3*6=18>>18 miles
On the fourth week, she walked 4 miles, 6 days a week for a total of 4*6 = <<4*6=24>>24 miles
Over four weeks she has walked 6+12+18+24 = <<6+12+18+24=60>>60 miles
#### 60