The ornamental design for a push up vest, as shown and described.
FIG. 1 is a front view of the push up vest embodied in the present invention;
FIG. 2 is a right side view of the push up vest embodied in the present invention;
FIG. 3 is a back view of the push up vest embodied in the present invention;
FIG. 4 is a left side view of the push up vest embodied in the present invention;
FIG. 5 is a top view of the push up vest embodied in the present invention;
FIG. 6 is a right side view of an alternative embodiment of the push up vest embodied in the present invention; and,
FIG. 7 is a perspective view of the push up vest embodiment in the present invention.
The dash-dash-dash type broken line shown in FIG. 2 to FIG. 7 is included for the purpose of illustrating environmental context and forms no part of the claimed design.