Part of the paleo lifestyle (because, frankly, I hate calling it a "diet") involves movement. Unless you're chasing down your food (or doing a lot of heavy farming), you need to get up and move.
Interval exercise is highly recommended by Robb Wolf. If you are a couch potato, start with walking for 5 minutes at a slow pace, then increase your speed for 5 minutes...and back to the slower pace. Repeat. Do as much as you can to start with and build up from there. Maybe try speed walking for 5 minutes then jogging for 5, etc. You get the idea.
Another aspect is resistance/weight training. You don't necessarily have to use weights at first - many of us can improve by simply using the weight from our own bodies. Some of the recommended exercises are squats, lunges and push ups. Don't let your eyes glaze over just yet - these are easy! Start by just doing what you can and do them at least a few days per week. Once you get comfortable, up the ante by adding more reps and/or adding weights.
You might think I'm a masochist, but this is one of my favorites. I'm not even sure how/why, but it's one of those tough exercise moves that I can power through.
Start with your feet shoulder width apart. Lower yourself into a sitting position. You can either pretend you're sitting in a chair or use an actual chair/box/stability ball. The trick is to NOT SIT DOWN. Hover! Once you feel your rear end touch the item you're "sitting" on, hold that pose. Stand up. Repeat!
The most important thing about squats is this: Do not let your knees go past your toes. That's very difficult at first, but it's better for you to have a shallow squat than to push your knees past your toes and risk injury. Your knees will thank you. The stronger you get, the deeper you'll find you are able to squat.
Lunges are another good lower body workout. You can do these in place or perform "walking lunges" - each lunge is another step forward.
Again, start small and work your way up. If you can't dip all the way down to a 90 degree angle, do what you can. Stretching beforehand can also help you get the most from lunging.
As with squats, be sure not to let your knee go past your toe on the front leg. Leaning too far forward will put stress on your knee and cause injury.
If you're anything like me, push ups are hard work. My legs are fairly strong because, well, they have to haul my heavy backside around all day long, every day. My arms, however, aren't accustomed to carrying much more than an armload of groceries or my increasingly heavy handbag. I'm not throwing spears or climbing mountains, that's for sure.
Start on the wall. This might sound silly, but you'd be amazed how much you can gain from doing 10-15 wall push ups a few days/week.
Stand with your feet slightly apart, about 1 ft from the wall. Place your hands approximately shoulder width apart at face level on the wall. As you lean into the wall, support yourself with your arms. Use the strength in your arms to push yourself back up to standing.
Once you're doing these with ease, you can move to using the edge of your bed or table. Maybe the arm of your couch. Then move down to a stool. Within a few weeks, you may find that push ups on the ground are not as daunting as they once seemed.
Do you have a simple exercise that has brought you some good results? A favorite you love? One you hate? Let us know!