If you’re feeling cold in winter, the solution may be a garment that is called Haramaki (腹巻, literally “belly wrap” or “bellyband”) in Japanese.
The one in this pattern is not only a tube, but has straps, too, so that it can be wrapped around your body and bound in front.
The piece is knitted flat and all in garter stitch and therefore quite easy to knit. It is suitable for beginners as well.

A danish translation of this pattern was written by Marianne Holmen of strikkeglad.dk - it is available here.