Just being 41 years old doesn’t mean that a person will not have diseases. It’s not a universal truth. Yes of course by passing age our body becomes weak and there are possibilities that person get soon sick. But same time as we are towards growing age our Aql I mean understanding power becomes more sharp and matured that is a positive thing by which we can do many things what we couldn’t do in our young age. As we know and it has psychologically approved that as much as we think about sickness we get more. As Imam Ali (a.s) said don’t go to the Doctor or Tabib frequently otherwise if you are not sick you will become sick.
If really you have some health issue I pray for May Allah give you complete Shifa but don’t think that others are fit and ok all of us we have some kinds of problem in our life and health issues.
As for as your liabilities concern don’t be worry about that just try to do your duties as Allah (s.w.t) has said in the Holy Quran :
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And that man shall have nothing but what he strives for. (53:39)
Therefore leave your affairs to Allah (s.w.t) and just try your level best always results are with Allah (swt).
As for as Dua and Munajat and Zikr, please if possible recite Ziyarat e Aashura followed by 2 Rakats namaz and Hadiya it blessings to Imam E Zaman (ajtf) (try to recite Ziyarat e aashura every day at a specific time which is suitable for you but keep reciting daily on that particular time. Better to recite after subah namaz when the sun is rising under the open sky at least for 40 days). Inshallah your many problems will be solved. Secondly recites this zikr s as much as possible ( La Hawla wa la Quwata illa Billah).
Thirdly always try to be with wudhu.
Inshallah soon you will get change.
Wassalam