Bikes and retirement aside, I’d recommend knowledge - career skills, but also handiness skills. If you can do simple repairs like replacing a door, changing the flap on a toilet, painting, preventative stuff like changing your air filters, simple electronics (replacing a light switch), etc you’ll save thousands on repairs as a homeowner. Today there’s almost nothing that you can’t find an in depth video tutorial on, but if you really don’t feel comfortable with basic tools most community colleges have cheap classes as do some hardware stores. Volunteering, even just to help friends with their projects, can be an amazing way to learn too.