runner starting to swim - please help!

[Myeaglewings]

So I love running. I don't really train, I just run for about an hour about 3x a week. I have recently started to learn front crawl - have been fortunate enough to book some 1 to 1 lessons and joined a nice gym for a month or 2 to practise. I have never really done front crawl before and can do the breathing now but am still very tired very quickly. I read that you only get swim-fit by swimming so decided to try push myself each time and go about 3x a week if I could. I work shifts, 2 or 3 long days a week, so figured I could run or swim each day I'm not working. But then I quickly pulled a muscle in my thigh, so on reflection I know I've overdone it, basically doubling the amount of exercise I was doing.
So my question is, how do I introduce swimming when I already run?? How do people do this?! Is the only way to run a lot less at the moment?! Should I ever swim and run on the same day, or never?? I do plenty of yoga stretches too and stretches for my core. I'd appreciate some advice - haven't found any despite trawling the internet!!!
Thank you kind people.

I swim run and cycle, i do a main swim once a week in the pool normally 40mins/1500m then I try to seaswim 2-3x a week but only 250m at a time which I cycle 15mins to, takes max hour so I do it on my ‘work from home’ lunch break or before breakfast. I run 2x a week a longer slow one on my day off and parkrun for speed on a Sat. I build stuff in around kids and work schedule, so if child is at an activity I’ll go run whilst they are there rather than sit in car waiting. My other DD does a long gym session in another town so I’ll go swim whilst she’s there. I walk the dog on the school run. I’ve always found just building into my diary and plan my intentions the night before helps me stick to stuff. If however I’m training for something like a HM I do drop other things as I don’t have more spare time just make different choices. Swimming is great for stretching out running legs but it takes time to refine FC technique, kids take 3yrs to learn it but as adults we expect to nail it in a couple of sessions. I self taught myself FC with the help of my club swimming DD giving me tips, still took me a good year to nail stroke w breathing comfortably but I still work on it constantly 3yrs later loads good videos on you tube like effortless swimming.

Thanks SkiRun the you tube videos look great x

i want to suggest 20 minute swim 3 times a week as a start & try to increase 5 minuts/session per week (so 20 minutes per session week1, 25 minutes/ session week2...) until you are doing at least 40 minutes/swim session.

When I say 20 minutes, probably allow a 1 minute break every 5 minutes to start while in pool, if you find it hard to maintain momentum in pool.

You go when it's convenient and ideally non run days.

Yes some days I run & swim, but tbf I usually run

Thanks lljkk I swam this morning and did a lot less with my legs!! and it felt much easier