I'm going to start resistance training and have decided to start with the Primal Essential Movements and then go from there. I also walk an hour a day with my dogs and do yoga almost everyday. I just want to start toning up as I'm nearing my goal weight (almost 100 lbs gone in the past 13 months) so I need to tighten things up.

I need to buy a pull up bar but the ceilings in my house are kind of low. I'm not that tall, 5'7", but the door frames in my house don't look as tall as what I see in push up videos on the internet. When I raise my arms in a a door frame my mid palm reaches the start of the molding. I think I'll definitely need to use a chair to start as I've always struggled with upper body strength even when I was relatively fit in the past. How do I do this in a normal sized door frame?