Comment by sambapa

1. Gymnastic rings - cheap, so simple yet so complicated. Magic ancient alien technology from the future (whatever that means) 2. Anki - free, you remember what you want to remember, but you have to RTFM to use it properly. 3. Wax earplugs - cheap. My sleep quality is at least 2x better since using them. 4. Org-mode - free.