Cant keep lower back on ground during core workout?

[autumn cedar]

I cant keep my lower back on he floor can you guys suggest me something for this?

[radiant steppe]

Its not the best advice but kinda just keep at it, especially if you're newer. As you do your core work put a good conscience effort to keep good form. I recommend doing daily practice with an easier variation while using the cue of trying sucking your stomach in. This kinda way of going about it helped me recently fix my pushup form which was pretty bad.