Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Future Me - Send an email to your future self
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Dabble Me - Your own private place to write. A journal/diary to help you remember what's happened in your life.
Slack - A messaging app for teams who see through the Earth!
Letter to my future self - Letter to my future self is a prominent email scheduling service that gives you the opportunity to create a letter with goals and thoughts for your future self and schedule a date for sending it.