and you find yourself squinting at it.
The ideally lighted painting will have a warm glow
dancing around the subject area.
Given average ceiling heights of anywhere from 8 to
12 feet, your tracks should be set between 3 and 3 _
feet away from the wall, this will keep the lighting
balanced. Further than this and the oblique angle will create
glare.  Any closer and you will not be able to light the
artwork properly and will invariably create hot spots. Should
you be placing your track on a peaked roof get a strong
enough bulb so you can hang it opposite the painting and
still illuminate the work.
If you have a high glare environment keeping
your light on during the day will help cut away the
glare and allow better viewing; however when you go to
sleep there is absolutely no reason to have lighting on the
artwork.
Plan for natural light settings as many of today's
homes have very large windows. You'll find paintings on
canvas deal well and display nicely in sunlight. Paintings
varnished in a less glossy finish have very little glare
problems and display well in natural light. If the natural
light is causing glare you cannot control, as a last resort I
would advise blasting the piece with light until you are able
to counter the glare.  This will sometimes work and
sometimes not depending on how powerful the glare
is.