You know everyone says that but I have never had a problem, but I guess it is how you take the pictures and manage them. I take all my pics with my phone, then I email them to myself and in doing so it will ask what size, I always choose medium and they always work.
For other pictures say from my digital camera, there are several ways to do it
1. go to the file where you have them stored, click on them and select edit (I am using a PC, so this is probably different on a Mac).
2. it will open the picture usually in Paint, then go to the top and click resize, a window will open and you can select pixels or a percentage (it will show 100 when it opens). If the picture is less than 2MB, I normally select 40%
3. save the picture under a new name (or not if you don't care). The picture should be small enough to post now but if not repeat 1 and 2 but this time choose like 60%)
The other way is to import the picture into something like Power Point, resize it and then right click on it and select "save as a picture". If you make the picture fit onto the slide it will probably be small enough (500KB or smaller).
The last way is to send/give them to someone else to fix for you...