Annually, glaciers are melting 8% faster than they did in the 2000s. While this might not seem like a lot, glaciers hold an important role when it comes to rising sea levels, causing floods in coastal areas. Additionally, glaciers play a critical role in influencing phytoplankton, which produce 50% of Earth's oxygen supply.
Forests (esp. rainforests), oceans, costal seas & fields have been impacted too by deforestation, poaching, industrial fishing etc.
"What Can I, The Average Human, do About It?"
Enough for the planet to heal. Sign petitions, donate to tree-planting foundations, volunteer to clean up sea garbage, plant trees, stop buying fast fashion, avoid buying fish from the supermarket and many. many. more ways.
"Even if I do these, the impact won't be enough to help save Earth. Nobody besides me is helping."
That's why "nobody besides you" is helping. Everyone besides the thousands of people who recycle, create petitions, plant trees, etc. believes their help won't be remarked, because others don't contribute.
Well, think about this: How many things have you done as a teen, a kid or even an adult, because you saw others doing it in your social circle? Enough. Make the change you want others to do. Be the example you want others to follow.
"Why would I make my life harder? The planet will die anyway."
Not everything noted here makes your life harder. Recycling, ecology, helping animals can even bring you a level of satisfaction on other hobby would do.
Even changing some of your small habits, makes a big difference, without being "painful".