There are three constant stalking horses for the next generations- War, Planetary Degradation, and Poverty.
War-People say it always been with us and its just human nature. But that's really a cop out and a lie to boot. You do not have to buy into it and feed their cannon. Humans have a natural aversion to killing each other and it's only sociopaths and psychopaths who wage war commit murder, rape, and a dozen other odious things. Don't be like those people at all costs! Seek the way of little conflict.
Planetary degradation- The idea the earth can be a giant garbage dump is a fallacy, since it's all we have and spacefaring to other planets is still a good distance in time in the human future, if we survive even to get to the point of making the choice to leave.
Poverty- You are responsible for yourself. Mommy and Daddy will no be with you forever. The earlier you get out to do what you want to do, the more that energy will last with you and help you defy the naysayers and killjoys.
Be careful with your carbon footprint and the creatures you take for your food. Huge corporations have spent trillions to create corporate oligarchies holding forth over the food you consume, and have processed most of the natural healthful constituent molecules out of them. They have tinkered with the genes of plants and animals, in some cases, mixing them, to bastardize the genetic inheritance of the foods which our ancestors most often consumed in a raw and wild state. Plant a garden and do what you can to feed yourself from that state of nature.
Learn to create your own wealth- most of it is in your mind.
Live in the Now- You are only as old as you feel. You can be "old" at 16 and "young" at 91. It's all in your head. Since it is all now that matters and all that matters is the now there is no use in staying behind and every purpose to move forward regardless.
The idea there is anything ending with death is a fiction, in the here and now, life is eternal, consciousness itself is immortal and the ground of being. The soul returns to fit the form & if it isn't possible to see the face of god one can see his reflection upon oneself in one's inner eye as a part of the whole.
The more people working to create a better world work together to create one, the faster an optimal evolved human world can come into being. The planet itself is finite and cannot itself be replaced- but we owe it to our future generations to discover those places which exist elsewhere in this galaxy which can be cultivated with whatever human descendants finally leave this planet for another.