When Moses came down from Mount Sinai with the two tablets of the Testimony in his hands, he was not aware that his face was radiant because he had spoken with the Lord. When Aaron and all the Israelites saw Moses, his face was radiant, and they were afraid to come near him.(Exodus 34:29, 30)
The fact is, the more time we spend in the presence of the Lord, the more of his radiance we receive. Here we read about Moses, who was in the presence of the Lord for 40 days. His face was radiant, though he did not realize it. But when Aaron and the Israelites saw him, they saw the radiance emanating from his face and were afraid that it might harm them. Moses put a veil over his face, so that no harm would come to them. We, as believers in Jesus Christ, can do many things that may qualify as being called "spiritual", but the best of these is spending quality time with the Lord in prayer and being overshadowed by his glorious presence.