What would you change in yourself if you had the power to change it?

There's a quotation from William Blake: 'He that would do good, must do so in minute particulars.' So although it's very tempting to want to make huge changes - eliminate world poverty, cure all deadly diseases, etc. - and I wouldn't discourage you from writing about that - if I had to do the essay, I think I might spend the first paragraph discussing whether I would want to make these global changes - and I'd then discuss the unforeseen consequences of change - or whether I'd want to make some small but significant changes. I personally spent a lot of time in South Africa in the run-up to the time when they released Mandela, and we had a lot of conversations along those lines; for example, 'which piece of repressive legislation would you repeal first?' and every one of them had tough consequences. (Note that this was before most people were aware of what Aids would do to the continent).