I find that the nimita approach of Ajahn Brahm doesn't work for everyone and that aiming to "see the light" can actually be a distraction to some (myself included). For me, the greatest hindrance to attaining bliss is desiring it, and that it's more effective to simply try to establish concentration (sustained attention) and then just wait and see what happens. Concentration alone without bliss is already very enjoyable, after all. I have gone for months without any bliss and then for unkown reasons it comes back for some time. Not sure really what the variations in conditions are...
"I do not perceive even one other thing, o monks, that when developed and cultivated entails such great happiness as the mind" (AN 1.10, transl. Ven. Bhikkhu Bodhi)
"So this spiritual life, monks, does not have gain, honor, and renown for its benefit, or the attainment of moral discipline for its benefit, or the attainment of concentration for its benefit, or knowledge and vision for its benefit. But it is this unshakable liberation of mind that is the goal of this spiritual life, its heartwood, and its end," (MN 29, transl. Ven Bhikkhu Bodhi)