Walking and running are the activities for which the counting of steps is most accurate.
The closer your smartphone is to your body, the more movement will be detected and therefore the more accurate the counting will be (the counting of steps will be less accurate in a bag than in your pocket)!
🚴 When cycling/biking, you can use Geovelo and read dedicated section on our helpdesk.
🏊 But... we don't recommend swimming with your phone... ;)