^ if youre not able to do strict ones yet, thats perfectly fine for progressing into strict ones! People usually bend at the knees instead of hips for progressing though. This has the advantage that you can bend your knees all the way every time, thereby making the resistance consistent (no need to wonder if youre getting stronger or just cheating more). Another advantage is that it will make sure your abs are being targeted directly and not as dynamic stabilizers since the abs are being flexed/extended and not the hip flexors which stay statically flexed.