On excuses Your circumstances, whether real or not, should not impede you from making progress. Your mind is the primary vehicle to move forward in any project, and even if the craftsman loses all of his tools, his brain can still function. He can still think about complicated problems that he needs to solve when he does get his tools back. This is making your time as alive as possible. When you are stuck on a train for an hour a day, you could let that time die and do nothing, because you say the circumstance does not allow for anything else—but your mind still works. Your brain can still process information, reflect on itself, observe, and make progress. There are no excuses for lost time.
On influence People are paying attention to you a bit more than you thought, and I can see it having a real effect on you. You didn't know that former teachers and friends knew what you were doing or even remembered you. But they did, just as you remembered them. Your words, written or spoken, have an effect on others. This is to remind you that no matter what you do, you have to acknowledge the people on the other end of your decisions. The things you say could either prove valuable or worthless to others. Your goal is to provide meaningful value to others, and that's it. Going through a 400-word exercise every day may not provide 400 words worth of value every day, but it will make you a better writer and a better thinker. If that's the case, then you must continue to do it because it will improve your ability to improve the lives of others later in life.
On experiences I recommend that you go out into the world and spend a bit more time experiencing rather than simply working. Specifically for you, I say you go out and get more experience meeting many different types of people from many walks of life. To someone else, I might suggest they get experience painting or doing more photography, because those experiences will directly impact their work. However, with your disposition that I've observed closely, all of what you do ties back to people. Developing an ability to write is developing an ability to pass information and influence along to other people. Becoming a better salesperson is learning how to best provide value to others. Improving your ability to publicly speak is practicing the skill of verbal communication—so that you can have a more meaningful impact on people. Your experience needs to be centered, though not exactly focused, on people. This will be the field in which you develop mastery.