Right now I am a sophomore going into junior year. When I was a freshman I was on the school’s soccer team. I’ve been playing sports my entire life and I planned to play throughout high school but unfortunately in the middle of freshman year I developed a lung problem which prevents me from playing sports. My doctors have no idea what the problem is so throughout my sophomore year I’ve had multiple visits to the doctor. I’ve also been struggling mentally for some time and without any activity or structure this year has been extremely rough for me. I also have doctor visits for that and i’m being medicated. But in the middle of sophomore year I switched to homeschooling for the sick because I was kinda going crazy, literally. Thankfully, I am now recovering. But I feel as if I ruined my chance to have a solid extra curricular activity because of all of this i’ve been going through. I’m planning on applying to pretty selective colleges like Penn state, Rutgers, MAYBE even more prestigious like NYU because I have good grades. Do you think that if I found a solid volunteering activity or two throughout the next two school years and joined a couple clubs or tutored or something like that would be good enough for these schools? I’m not really sure what I’m passionate about because i’ve been in sports for a long time(i only liked playing them, i don’t want to manage them) so after getting my lungs hurt i’m kind of forced to do other things. But I really want to have a few solid activities for the next two years so that I’m NOT doing something new every month. I’m pretty open to a lot of things. What do you guys think I should do?
Also do you think all of the medical circumstances would affect getting into these colleges?
holy wall o’ text. use the carriage return. Medical past will not keep you from college unless you are unable to attend. Explore a few thing that may catch your interest. Since you are stuck home a lot, research ‘citizen science’ things on the internet. Maybe you can’t play soccer but you can go on a paleontology dig or just do things from the computer. Explore creative outlets. when you find what you like, deepen your commitment. Read a lot. It is too bad you are in this situation when you like sports so much. I have an athletic nephew but he has congenital lung problem and is in the hospital every year at least once. He had to do that home hospital and hates it because he wants friends. but sports aren’t necessary for college admissions.
No, this won’t hurt you if you have managed to keep up your grades and you test within the acceptable range for the schools you are targeting. You had a serious medical condition and did what you had to do - schools will respect that decision.
For the coming year, your job, apart from staying healthy and on track academically, is to develop some relationships with teachers who can write good letters of rec for you and find two or three activities to try out. This is not about developing a laundry list of ECs - it’s about figuring out what you enjoy besides sports if that’s no longer an option. Don’t feel badly if you try something and it’s not your thing. For most schools, ECs are just a way to show that you can engage in a community on levels other than the academic one and that you are interested in new experiences and expanding your horizons. Those those are more selective want to see some level of accomplishment in your ECs but your experience as a sidelined athlete who experienced serious health issues also gives you a unique perspective which they will also value. Have you considered ECs that involve working with others who experience physical or emotional disabilities? Or medically-related volunteering if that area is potentially of interest to you long-term? Or tutoring for those who, like you, need some alternative academic support during a difficult time? All of these are ways to take the lemon of your disability and turn it into a more palatable beverage.
I don’t think teens need to find a “passion.” You’re supposed to be exploring and learning. We’re homeschoolers so we don’t have access to public school sports and clubs, but we’ve always encouraged our kids to participate in whatever community activities we could find. They didn’t have to do the same activity (so they weren’t looking for a "passion), but they did do the same types from year to year: a sport or athletic class (yoga, golf, archery, karate…), community service (soup kitchens, senior centers, animal shelters, community events…), and an elective that they wanted to explore (computer coding, filmmaking, art courses, music lessons, cooking classes, forensic workshops…), etc.
Think about what you already like to do and see what’s available locally. If you’re still healing, don’t try to take on too much at once. I encouraged my children to think about what kind of people they wanted to be and focus on that. Any college that didn’t value that wouldn’t be a good fit. My son was accepted to Penn State but decided to attend our state university so he could graduate with no/minimal debt.
Good luck. I hope you feel better soon. 
Find other things to do and you will be fine. There is an “additional comment” section of the common app if you feel you need to put in a couple of sentences (not as much as above) saying due to health issues you had to give up sports, were home-schooled for a while and now that your health is in control, you have moved on to other meaningful activities.