I can't either at 64 year old. The most yardage that I have done in workouts is 2,000 this year. Usually between 800 to 1600 yards. I like doing all four strokes and not all freestyle. Probably, breaststroke the most since I like kicking breastbone on the board. Unlike Michael Andrew going 15 seconds on each 25 yard is too hard for me as well. I do 25 yards at 30 to 1 minute rest. In fact the workouts sometimes they give I couldn't do in my 40's either when I still did a 1:34 100 yard breaststroke. I have swim one 200 yard fly at 4:50 in workouts.
Everything is relative, really. If you are a triathlete or swimmer/runner, those times are quite respectable. If you are competing in just swimming events, you won't win Nationals, but you know, who cares? What are your goals? If you were a non-swimmer who just recently got into swimming a few years ago, then 1:20 is pretty good for 100 meters. I am a former swimmer who got back into swimming as an adult after a long layoff, and my masters' best is 1:10 and change, but I'm in my 60s. You didn't say how old you are, so that is another factor.