Yes, I'll say it. Modesty is not hard at all. You don't have to dress like an Amish woman or a Saudi Arabian. If your neckline is too low put on a camisole or add a strip of stretch lace or get out the safety pins. If your pants are too low make sure you have on a tunic, an undershirt or better yet, just skip low-riders altogether. Pants seem to be a blood-in-the-eye subject for some Catholics which is too bad. Simply remember two things: your age and the situation. I don't care how much you exercise, tight jeans and jeggings make women over 30, look like Miss Haversham. Lectors and ladies bringing up the gifts at Mass need to know that when they bow in pants, nine times out of ten, the view from the pews is not a lovely one.
If you wear a mini skirt --- and come on, you shouldn't, then at least wear dark opaque tights with it. If you have to wear shorts stick to Bermudas and capris. There is no legitimate reason to be seen in public in Daisy Dukes.
If you are have dress that lacks a lining and is in a thin material put on a slip. You may scorn slips as old fashioned but that humble little garment prevents you from having clinging fabric, see-through incidents, and they save you from the cringe inducing moment of when you realize that you've been walking around unaware that your dress was hiked up in the back and you've been mooning the town.
Your underwear should be unseen. There's nothing more to say about that. A strapless dress doesn't belong in church, (take note brides) and at best not before 8PM. If you must go strapless then it should be a long, very formal dress. As for swimwear you don't need to wear a bag to the beach or pool but there's no legitimate reason for a bikini and certainly no reason to be seen in a thong. Buy a one piece with brief cut legs or a swim dress and you'll be fine in most circles. Modesty--- of course you can do this. It's easy.