Training. Swimming - the least favored session

I grew up as a swimmer, my earliest childhood memories are of early mornings, chlorine, and always feeling wet (wet hair, water in ears, wet towel in school bag, and worst of all wet pants when you forgot to pack underwear and had to where the swimming suit from the morning session for underwear).

I was once able to complete 5 to 6 k sessions in a canter.  A 1k warm up was pretty normal.  At my very best I was somewhere around the top ten in the country for my favored event (50 m freestyle) getting it all done in under 23.5 seconds.  Well that was back in the day, and now is now.

Today I did my first swim session in a while and it wasnt pretty.  The session was basically:

Warm-up.  400 free, 100 brst

Main Set.   10 x 50 free @ 80% on 1:15 interval.
(averaged completion in 42-44 s per 50)

Dev Set. 4 x 100.  alternate kick/pull

Cool Down. 100m free, drills.

While it felt crap I did stick to plan and I'm confident I'm ready for the 750m swim I have on Sunday and pretty sure I'll be ready for the 2k swim in June, but the 1500m in March feels at risk.  I so need to get back into a regular swimming regime.