Obtain a smartphone. It will make your life better. (If you don't have one because you feel like they're overhyped, remember that reversed stupidity is not intelligence.) Here is a list of things I use my smartphone to do, in no particular order:

• Record things I want my future selves to do in RTM on the go
• Record sleep data using Sleep Cycle
• Take notes on conversations using either voice memos or Evernote
• Record various kinds of things in Workflowy, e.g. exercise data
• Respond more quickly to emails (people I know have debated the value of doing this, but I get really annoyed when other people take a long time to respond to my emails and don't want to do that)
• Receive calendar alerts, alarms, and Boomerangs from my past selves that remind me to do things
• Look things up, e.g. on Wikipedia, on the go (e.g. when I am waiting in line for something)
• Read academic papers on the go
• Search my email for important information on the go, e.g. the location of some event or an ID number of some kind
• Look up directions on the go, e.g. to the location of some event
• Look up places on Yelp on the go
• Look up prices and reviews of an item I'm considering buying IRL on Amazon

There is a possibility of wasting large amounts of time playing games which I curtailed early on by refusing to download games except during breaks from school.