How am I supposed to work out at my age (57) when I have no energy? I'm sitting at my desk at work at 3:55 p.m. CDT right now and I can barely hold my eyes open. I am so sleepy.
You might want to check in with a doctor about your low energy. Here's a serious answer to your serious question:
I'm 64 and doing the STS Strength series for the first time, and it's going well. I get sufficient sleep (it varies with the season), eat for energy and health (main meal is a super-heathy protein/fiber smoothie for breakfast, similar to one Cathe posted in recipes section), and stay hydrated (very important for energy and mental acuity). When I eat, I try to make it tasty, but the real criteria is how I feel in 20 minutes, an hour, four hours out, and at the end of the day. I used Cathe's food planner for a month to balance my nutrients using real foods, instead of relying on vitamins, and that was helpful. It was more comprehensive than the app "My Fitness Pal" for tracking food. If that's too complicated, get enough protein, and have 2-3 servings of veggies/fruit with each meal. Cut back on processed carbs (sugar, white bread, etc.). Sugar and processed white flour can make susceptible people sleepy, so I mostly avoid them. There's plenty of info and plans out there. If you always feel tired at a certain time of day, eat some nuts and fruit just prior to that, and take a walk down a hallway or up some stairs to get your heart rate up a bit and your blood oxygenated and circulating. Don't huff and puff and exhaust yourself, just move. Think about something really nice to enjoy after work - it lifts your spirits. Maybe it's a lovely view you'll pass on the way home, beautiful music, a colorful salad you'll make for supper, the bliss of a hot shower, or a quiet read before bed. It will pull you forward and put a little life into you.
Assuming your health is okay, I think once you start to work out, your energy and spirits will lift almost immediately. Begin gently and work up to more, and this is important. As we age, our connective tissues (muscles and tendons) aren't as flexible and don't recover as quickly as they used to, which can leave you open to injuries that will sideline your workouts (been there). So take it gently and let your body build itself up to harder workouts later. Walking is excellent, but I've learned not to over-stride (more effort isn't always a good thing). If you feel exhausted the next day, rest and go at it more gently the next time. Keep going. Progress may be slow, but it's there. Without a fitness watch I would have given up after a summer of walking, but testing indicated I'd made real progress internally, so I kept going. The progress will be there, whether you wear a device or not. Slow walking can do you more good than fast-paced walking. Interval training (fast/slow/fast/slow) is even better, but you don't need to do that for a few weeks.
Cathe's workouts have been safe for me, but if I'm having trouble (pushups!) I modify as much as necessary, and make sure I don't get injured so I can keep on going the next day. Good form is a priority to avoid injury and get the most benefit from each move. Watch your form! Be smart and apply ice if you're sore the next day. It works.
Like driving in snow, it's not how fast you go, it's how far you get! My personal goal this year is to head off to age 100+ in great shape to enjoy a fully active, happy life and avoid the doctor's office, which means daily exercise for the rest of my life. I plan on building a solar aquaponics greenhouse (myself!) next summer to grow veggies, so I'm building muscle and stamina now. Take care of your body like you're going to need it until the end of your life. I've seen super-fit seniors, and visited relatives in nursing homes, and realize if you want to stay healthy, you need to do what it takes. It is possible.