The ornamental design for a activitymonitor, as shown and described.
FIG. 1 is a front, top and left side perspective view of a activity monitor, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is an enlarged cross sectional view thereof, taken along the line 8-8 in FIG. 5 with its internal mechanisms omitted; and,
FIG. 9 is an enlarged cross sectional view thereof, taken along the line 9-9 in FIG. 2 with its internal mechanisms omitted.
The broken lines in FIGS. 8 and 9 are included for the purpose of illustrating portions of the activity monitor that form no part of the claimed design.