Interestingly, I am just beginning a class on Life Span Development in my Psychology major. From the brief overview I read yesterday, it is expected that the "early middle aged" will be happier and less stressed. I fall into that category of age.
I do think though that it depends on what stage of life you are at, and not just on your age. Many people of my age have fully grown/flown kids and are thinking about retirement in ten or so years, and relaxing, whereas my youngest child is 14, my eldest is still at home and working through his post college certification so he can finally start his career (and leave home!!) So, I have a way to go with the 14yo before he will be trying his wings, and as I am a junior in a college program and intend to go to graduate school next year, I am obviously also looking for a career change, rather than heading into retirement. In fact, if I can pull off my career change, I would be glad to keep on working (even if just part time) for a long time to come. So I am still pretty stressed and often struggling to find enough hours in the day. But I am probably a very small percentage of the population for my age group.
This age we definitely are losing loved ones. Both of my parents are gone. Shockingly, some of my contemporaries are gone too. Many of my friends have lost their parents, in fact it is a rarity when someone my age tells me that they have parents still alive. Health problems is a given as are precautionary measures. As I approached 50, my primary doctor would cheerfully send me brochures to remind me that I would be getting my first colonoscopy at age 50. Yes, happy birthday Hetta, now come and let us stick this tube up your rectum. :o However, my health is good, and it is important for those in their 30s to champion their health with healthy eating, exercise, regular check ups etc. so that they retain that good health.
You can open an IRA at any age, once you have a regular income. Both my dh and I have retirement savings in place. I'm not too concerned about that at this point. Ask me again in 10 years.