A different reply said they waited until 26 to start - that is probably about the right time to start saving for retirement. Maybe a little late, but close enough. Before about that age you are still getting started and so you have little spare cash. You need to pay off school loans (if you took any). You need to save for down payment on a house, and buy a lot of those will last a lifetime household items everyone needs. You should be thinking about marriage and saving for it (even if you don't get legally married most people will live with someone else and should be planning on how to make that life work).
Most important: you don't know how long you will live. Save for the future, but not everything - you have no guarantee you will live to tomorrow - if you are under 60 odds are strongly in favor of it, but people die young all the time. You should have a little play money as well in your budget. Go climb Mt Fuji while your body is young and healthy enough to do so (I picked a random activity here, you should decide what you care about, not rush to Japan)