Help! My core is shot.

[Lovepeaceunderstanding]

I do hope someone can point me in the right direction. 🙏🏻
Im 61 and have neglected to keep fit but have now started an exercise routine which includes weights and HIIT on a static bike three times weekly. In addition I do yoga, usually twice weekly and my husband and I ballroom dance once a week. We intend to also incorporate a gentle stroll for about half an hour most days which for some reason seems to be the most difficult thing to actually get started. 🤷‍♀️
My problem is finding an abdominal exercise I can do, I think unfortunately that my abbs are so non existent that I can’t adequately perform the ‘crunches’ my husband has suggested. Do you know of a core exercise that can build up the strength in my core, thank you so much if you can help.

Pilates, either reformer or mat is perfect for building core strength and great for mobility and flexibility

Please don't crunch! Planking will massively help your core and there are so many variations you can adjust to your ability - low plank, high plank, side plank, one leg/arm. Yoga should definitely be helping too, as long as you remember to engage your core when practising (which basically means pull your tummy button towards your spine)

I'm the same age and have found mat Pilates 2-3 times a week excellent for both my core and general flexibility. It took a year or so to stop feeling like I couldn't move the day after because my core ached! If I take more than a week off I decondition really quickly. I've come to think of Pilates as medicine that needs to be taken regularly

Planks! If you struggle with a full plank you can start on your knees. Yoga and ballroom dancing will also engage your core. Actively engaging it as you move around doing your daily activities can be helpful.

You could try standing core exercises or a gentle barre class. They strengthen your whole core without doing any kind of sit ups.