Change the blending mode to Screen then position the light behind the model. You can use the Free Transform tool (Ctrl/Cmd+T) to see the bounding box of your layer which may help you see where it is moving but this isn’t necessary.
Go to Filter > Blur > Gaussian Blur. Set the Radius to 43 pixels then click OK.
Press Ctrl/Cmd+Shift+U to desaturate the lens flare. Use the Free Transform tool (Ctrl/Cmd+T) to scale down the lens flare. You can also reduce the opacity to 60% if you’d like.