Start where you are now. You really can’t start anywhere else. You can “if only” yourself to death – you know – “if only I had majored in something else in college,” “if only I had gone back to school 4 years ago,” if only I hadn’t done that thing I did.” None of that makes any difference, because you either did or didn’t; thinking about how you would do it differently now doesn’t make it happen differently in the past. Start where you are right here and now, and do that thing that’s important to do. Regrets don’t get you anywhere new, they just keep you mired in the past. What is important for you to start now?