The thing is that if I could travel to the past, the thing(s) I would do to change my future wouldn't be small at all, though.

I would give myself winning lottery ticket numbers, what to trade on the stock market, when to buy and when to cash out. Who to avoid in life, who to make sure I cherish more, etc.

I would do things that are small compared to the rest of history/the World, but I would give myself all the advantages I could think of.