The ornamental design for an exercisedevice, as shown and described.
FIG. 1 is a top, perspective view of the exercise device; the view showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a side elevation view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a bottom, perspective thereof.
A description of the appearance of the article is as follows: An exercise device, the broken lines showing portions of the design in the figures are included for the purpose of illustrating environment and unclaimed features and forms not part of the claimed design.