Sometimes people think that once their education for a formal career is done, there is no longer any need to look for other opportunities to learn. That might work for some but the fact is that we need to keep our brains engaged.  Like the old adage says, use it or lose it.
What can this added learning be? Anything and for any reason. Whether it is merely an interest or pursuit of a side hustle, it doesn't matter. Learning opportunities are everywhere.  
This podcast includes how to find free opportunities to expand knowledge and others might cost a fee dollars. Take a listen to see if there is anything that will inspire you to carry on becoming a life-long learner.