How do you sit if you are not flexible and find sitting cross-legged difficult?

I sit with my legs straight in front of me sometimes, otherwise try kneeling, or just get close to crossing your legs but stay comfortable

My thighs are too large to cross my legs. Plus this creates broken capillaries (varicose veins)
Sit like a lady, knees touching right foot on toe slide behind left foot- to the left. Knees pointing toward the left.
Or right foot behind left foot .
Straight back.
Do not slouch.
If you are at an interview do not sit up against the back of the chair.

Well, for starters, a chair. Theres no need to sit on the floor and at several meditation practises they explain that. Apart from that you could start doing Yoga. Yoga is a series of postures that simultaneously develop lots of bodily consciousnes while improving flexibility and making it possible for you to sit in lotus position in the long run. Yoga is a preparatory practise for meditation and much more. It even induces a similar state of mind!