I'm writing a story in the first person in which my main character is the narrator. Sometimes he describes events that have happened and sometimes he describes situations that currently exist for him. In my text I end up with statements along the lines of, 'This is what I did' and 'This is how things are' but one is in the past tense and the other is in the present. Would it be all right to swap between tenses like this? I could write both in the past tense by saying, 'This is how things were' but wouldn't that imply that something has changed and the current situation for the MC is different? Would it be better to write everything in the present tense?