Decluttering - why do I find it hard to make decisions!

[Jemster]

My house is far too full of 'stuff' and I'm trying to gradually declutter. I'm finding it hard to make decisions at times about getting rid of things as I keep thinking either what a waste or what if I need it in the future.
Thinking like this makes progress slow but I just can't seem to make decisions for example on:
Books - several practical books on childcare, housekeeping & gardening! Never got round to reading & been sat on shelf for years.
Nice undewear worn once on wedding day - will probably never fit me again!
Gym clothing - cost alot but now too tight.
Kids stuff, toys, books, etc. Some are rarely played with but they do want to occasionally so I can't bring myself to get rid of any especially as toys are so expensive.
Bday cards - I don't keep them all but have big stacks I've kept from 'special' birthdays, I can't bring myself to chuck them.

I'm finding it hard living in an overflowing house that I just can't manage properly.
Does anyone have any advice please if you've felt the same? Thanks

Underwear - chuck or get a beautiful box/paper to properly store it

Books - chuck

Rest - rotate toys/chuck

Am ruthless Have you read Marie Kondo?

I'm going to say it too. Marie Kondo.

She's a miracle worker!

Thanks I have had a very brief look at Marie kondo. Some people have said she doesn't talk about organising kids stuff? Also it's trying to get everyone else in the house to follow a plan & I'm not sure how easy that would be! Worth a further look anyway.

She doesn't have children, and for me, she is too strict in the area of emotional items, but some don't agree. I follow her ethos quite loosely but it has still helped a lot. It's worthwhile looking at some of the threads about her book on here.

Marie Kondo
You don't have to agree with all her idea's but she changes your mind set and makes it easier to make decisions.
The threads about her book are great too

You don't have to follow all of it though

Her technique is to gather everything that is the same in one pile in middle of the floor (for example books) and ask each book if it makes you happy/joyful/desirous to keep - then you get rid of every ones that don't

Could you scan the special cards and save them on a Pinterest board or Facebook album (both of which can be kept private or made public) and then bin the real things?

That way you can still look at the pictures and messages if you want to, and by saving them to one of those websites you won't lose them if something happens to your computer, but you won't have them taking up actual space in your house.

Get rid of the books. You can go to the library or look on-line should you need to in the future. I say this as a book hoarder who was just last week took several hundred books to the charity shop and only regretted giving away one of them. I still have hundred's more in the house, but they are tidier, more manageable and more likely to be read now.

Ebay the too tight gym clothes.

For the children's stuff, why not do what my mum used to do with us - ask them to choose things they don't play with much to give to other children who don't have any toys? Pretty sure my mum donated the stuff to charity when we just had too much clutter.