I am 48 and cruised alone for the first time last year and had a blast. I was nervous at first, but once I let my hair down and decided to go with the flow, I began to relax. The only drag is eating alone. I went on NCL. They have the freestyle dining, so you don't have an assigned time or table. This was a drag because they put me with 1 couple the first night (boring) and totally alone the second (really boring!!). I am going on my 4th cruise in September (2nd alone) on the new Mariner. The single supplement is a bit steep, but to me it's worth it to have the cabin and balcony all to myself.
Hope this helps....
Kathy (cruise addict)