I'm a 52-year-old man trying to get back in shape. I've been using resistance bands and can do about 8-10 pull-ups with assistance, but push-ups are really giving me trouble. Even doing them on my knees is a challenge. I started a fitness routine about a month ago and can use 10-pound dumbbells for chest exercises. Pull-ups were tough at first, but I've made good progress. Push-ups are a different story - my form is poor, my arms shake, and I can barely hold a plank for 20 seconds. Any advice for building up to proper push-ups at my age would be greatly appreciated!