Convex Heart

Ctrl + click the heart-layer. Grab the Dodge Tool and set Brush to 65 px (soft round), Range to Midtones and Opacity to 15-25%.

Imagine the heart in 3D. Do slowly brighten spots on the heart. Don't bright the edges.

Repeat brighten the heart. Grab Burn Tool and set Brush to 45 px (soft round), Range to Midtones and Opacity to 100% and do slowly darken the edges.

Duplicate the layer and select the new layer (ctrl + click). Go to Channels-palette and Create A New Channel. Fill the selection with #FFFFFF.

Go to Filter > Blur > Gaussian Blur and set it to 4.0 px. Repeat the step by hitting Ctrl + F. Go back to Layers-palette and activate the duplicated layer. Go to Filter > Render > Lightning Effects and use these settings:

Remove the selection (ctrl + d). Set Layer-mode to Screen in Layers-palette and maybe a little Inner Glow.

You are finish.