Read Rilke’s Letters to a Young Poet.
On writing and rejection:
You ask whether your verses are good. You ask me. You have asked others before. You send them to magazines. You compare them with other poems, and you are disturbed when certain editors reject your efforts. Now…I beg you to give up all that. You are looking outward, and that above all you should not do now. There is only a single way. Go into yourself. Search for the reason that bids you write; find out whether it is spreading out its roots in the deepest places of your heart, acknowledge to yourself whether you would have to die if it were denied you to write.
If your daily life seems poor, do not blame it; blame yourself, tell yourslef that you are not poet enough to call forth its riches.
On “owning” your work:
…[I]f out of…turning inward, out of this absorption into your own world verses come, then it will not occur to you to ask anyone whether they are good verses. Nor will you try to interest magazines in your poems; for you will see in them your fond natural possession, a fragment and a voice of your life. A work of art is good if it has sprung from necessity. In this nature of its origin lies the judgement of it: there is no other.