In most states the licensing for a commercial Realtor is exactly the same as it is for a residential real estate license. Just getting licensed isn’t going to allow you to walk into a 70k-100k/yr job, but will likely see that or more if you know what you are doing. Being a Realtor is a 100% commissioned job and it takes time to build your business. Amongst the successful commercial Realtors I know, like my brother, they all have the CCIM designation which is what they refer to as the PhD of commercial real estate.

As far as starting in middle age depends alot on how well you have networked thus far. The majority of commercial Realtors I know are between the ages of 33-60.