Phone
Use an iOS app such as Moment app, or your phone's built-in feature
Remove your phone from your study space
Put your phone on "airplane mode" to limit notifications and distractions
Computer:
Install the Chrome extension UBlock Origin to removed distracting ads
Install the Chrome extension LeechBlock (video) to set limits on the websites you see (can customize and set timers)
Install the Chrome extension Beeline Reader to stay focused on the text
Install the Chrome extension Block Site to set timers and block sites temporarily while you work (2 sites)
Watch a 2 minute tutorial video to see how Block Site works, including the Focus Mode
Try the Chrome extension WebTime Tracker to track where you spend your time online! Are you really on-task all day??
Play white-noise while working. Research has found that music with lyrics decreases productivity!
Listen to the rain via this website
Search for study music on Pandora, Spotify, or YouTube (this site has background music from YouTube)
Try a computer-based app such as Rescue Time to set goals, monitor those goals, and receive feedback about how you use your technology
Pomodoro Timer app - Learn more about the Pomodoro Technique and how you can do it without an app!
Use the Focus time feature in the Block Site extension as a Pomodoro timer
Try the Forest extension for 30 minutes "on"/working and then a 30 minute break.
Create a checklist for the specific work block. Checklists are easy to create with Google Keep.
Set a timer for an interval (perhaps start at 5 minutes). Each time the timer rings, get back on task. Or try a more sophisticated app for behavior change such as MotivAider.