I have spent the last 2 out of 13 years living on a part time basis. This sounds odd but it has changed my life. I am more relaxed and consequently get things done, although rather slowly. Sometimes I feel 90 but I have gotten very good at acceptance.
In short I have a 2 hour window. Meeting friends, a bit of shopping or gallery visiting and I call it a day. Friends understand the rule. What it means is that I can do other things in the day you know like cooking, eating - just staying awake. If I obey the rule I can also do things the next day rather than having to rest for 2 or 3.
My body cannot cope with noise, vibration or stress so I avoid this as much as possible. Fortunately, I have a heated car seat - a blessing on a long journey or if the roads/pavements are rutted causing my muscles to have to adjust a lot. Ear defenders also take the edge of the constant loud intrusive music forced on us in shops, high streets etc. Avoiding crowded situations also reduces stress which again gives me more time to do normal everyday things.
Finding what works for you takes time and it is not failure to accept that life has to be adjusted. Take a deep breath and go with what is best for you - live your life.