Shoulder press and chest press could be the two to-do-exercises that could be used to increase ability to perform push ups in a fitness evolution.
The above stated two exercise are strength based it means that it will help in building up the stamina. And will also provide strength to the upper body part which plays an important role in push-ups.
Beside these two exercise curl ups can also help in building up the stamina. These exercises also known as weight training exercises. Push-ups also help in well working of cardiovascular muscles that is proper functioning of heart.
They are probably stage three, because when you are stage three, There are three symtoms, which are Isolation/ Legal Problems/ Depression. Isolation is one that he experiences, so when someone asks him how much he drink, he does not reply, or he lies.
So look up the symptoms of autism that could cause difficulties with teaching him how to swim and how to work around it (patience is key) if you need the symptoms just ask I'll get the real quick
look up difficulties that come with Alzheimer's and a way to help the 81 year old like maybe catching a tossed ball and walking with a dog around the nursing home (patience and encouragement)
look up brain injuries and exercise that might help with him it's important to encourage him to keep going
look up alcoholism maybe keep her mind and body occupied like word puzzles and exercises again patients is key