In most cases, cutting off the circulation to your foot by crossing your legs is the reason it goes numb. The blood vessels around your knee can get compressed with leg crossing or other contorted positions. Furthermore, the nerves that innervate your foot muscles are positioned next to the blood vessels, so some nerve entrapment or compression is not unusual either. As such, simply change your position by uncrossing your legs so that your foot gets its proper blood supply and nerve input. The foot that you cross over is typically the one that "falls asleep." As the blood starts to flow properly into your foot again, it should feel a little warmer and somewhat prickly for a few minutes. In addition to changing your leg position (if leg crossing caused the pins and needles in your feet), stand up from your chair in order to promote better circulation. When you stand up, you enlist the help of gravity, which helps pull the blood from the upper leg into the foot. Arteries have smooth muscle fibers that contract and push the blood down in correlation with your heart beating, but standing up might make the process occur a little quicker. Moving your foot in all directions (circular motions for 15-20 seconds) will likely help with circulation also and reduce the numbness or pins and needles sensation a little quicker. While standing, a light leg stretch (such as bending at the waist and trying to touch your toes) might help "wake up" your feet also. After switching positions and un-kinking blood vessels and/or nerves of your lower leg, consider walking around to promote better circulation. The main caveat here is, make sure your have some feeling and normal strength in your foot otherwise you risk tripping or collapsing and causing an injury. Once you change your position, pins and needles in the feet don't last for more than a few minutes. Permanent foot damage can occur if blood flow is restricted and nerves are compressed for many hours. Simply shaking your asleep foot may be a safer alternative to walking if you still feel significant numbness or pins and needles. Pins and needles and/or numbness of the foot is sometimes caused by poorly fitting shoes. Cramming your feet into a narrow shoe is not good for circulation or nerve flow and may cause your feet to fall asleep particularly if you walk or stand a lot. As such, choose shoes that grip your heel tightly, support your arches, provide enough room to wiggle your toes, and are made of breathable materials (such as a leather insole). Avoid wearing narrow-toed high heels. If your foot symptoms are primarily on the top part of your foot, then try loosening your laces. Get fitted for your shoes by a shoe salesperson later in the day because that's when your feet are at their largest, usually due to swelling and slight compression of your arches. When at your desk at work, consider taking your shoes off so your feet are less constricted and can breathe. In some cases, pins and needles in your feet might be caused by tight or strained muscles of your lower leg, such as your calves. Soaking your feet and lower legs in a warm Epsom salt bath can stimulate circulation and significantly reduce pain and muscle tension. The magnesium in the salt helps the muscles relax. If inflammation and swelling is a problem for you then follow the warm salt bath with an ice bath until your feet feel numb (about 15 minutes or so). Always dry your feet thoroughly before you get up and walk away from your foot bath in order to prevent slips and falls. A dietary lack of minerals (such as calcium or magnesium) or vitamins (such as B6 or B12) can contribute to uncomfortable symptoms in your feet and legs.
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One-sentence summary -- Change your leg position. Stand up. Walk it off. Wear shoes that fit properly. Take a warm foot bath.

Find qualities that you admire in others and that you want to learn. If you can't think of any right away, think of people that you wish you were like and think about what it is about them that you like. Are they kind? Ambitious? Hard working? These are qualities you should look for. Think about the things that you don't like about yourself. Don't focus on things like your weight, because your body is really just the container you're in, it's not who you are. Things like weight should be tackled after changing stuff like your attitude towards others, your work ethic, and your skills. Think about what you want to change. These have to be things that you really do want to change. It's true what they say: the first part of solving a problem is admitting that you have one. Figure out what really means the most to you and what would be motivating enough to change your lifestyle. Talk to others that you trust, like lovers, friends, and family members. Tell them what you want to change about your life and why. They might have some good insight that can help you in bettering yourself, as well as a clearer view of who you are as a person. Start with small goals. Don't start with something like "stop smoking". Instead, try "smoke less". Breaking goals up into smaller goals will help keep you motivated and make your goals more realistic. Think about where these goals sit in your life priorities. This can really change how much effort you put into bettering yourself. If you don't set a deadline for a change, the goal will feel unreal and intangible, and you'll be less likely to complete it. Start! Don't just think about goals or what you want to do, go out and do them!
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One-sentence summary --
Identify qualities you admire. Identify your flaws. Decide what you want to change. Get input. Start small, work up. Decide on a timeline. Follow through.