Posting one thing on Twitter every day that I think will be valuable to someone. It's part of showing your work, which is important when building a bootstrapped solopreneur business. I've met clients and valuable connections that way.
It's a great way of getting out of your shell, become used to criticism both positive and negative, connecting with like minded people and get a momentum or habit going. I even distinctly remember a book called micro-habits that was about this concept.
How long have you been writing a tweet a day for?