Your are your 'selfish' years. It's a decade to immerse yourself in every single thing possible. Be selfish with your time and all the aspects of you. Tinker with shit, travel, explore, love a lot, love a little and never touch the ground.
The sun will rise again tomorrow, so if something didn't work out today, try again tomorrow or the day after. With chronic illnesses, fatigue and pain will often change or limit your plans. Don't worry--let it go. There's still time.