What research says about affirmations
Value affirmations have good evidence. In psychology, "self-affirmation" usually means writing briefly about a value that matters to you, like family, creativity or honesty. Geoffrey Cohen and David Sherman's 2014 review in the Annual Review of Psychology describes how this can lower stress and defensiveness and, in some school studies, narrow achievement gaps.
Grand statements can backfire. Joanne Wood and colleagues (2009, Psychological Science) had people repeat "I am a lovable person". Those with high self-esteem felt slightly better; those with low self-esteem felt worse. The likely reason: a statement that clashes with what you believe invites your mind to argue back.
That's why the affirmations here are phrased as processes and values ("I am learning…", "I choose…") rather than as finished facts. For the bigger picture on positive thinking, see what research says about manifestation.