At first I thought this was talking about a king, then the sun and back to the king. It gives off the impression of it being a king many times with out stating it. When it says that he attends on his Golden Pilgrimage and
unlooked on
diest unless thou get a son. Kings tend to be rich and they tend to want sons (no offence to a king if he reads this). This is what I think happens in the poem, the king has climbed up a steep heavenly hill to look at the rising sun. It then implies that the king is strong, even though he is middle-aged but normal people still adore his beauty. But when he is at a feeble/old age, he dies, or reels from the day. I don't know what the next few lines mean but the last line could mean that before he did die he would have to have a son which he didn't. Maybe it was through some sense of pride that made him want a son, not a daughter.
This is my interpretation of sonnet 7... for now.