First, it is not a silly question, I would wager some of the greatest minds have pondered this question. It is a mindless person who accepts whatever they are told without questioning it.
Second, no one answered the question. Do our actions make a difference? If we go on a diet, quit smoking and drinking, could it prolong our life? Will God allow us to live longer if we do so, or has our number of days been determined before the foundation of the world and nothing we do can alter it?
The doctor has to tell you what he has to tell you, even if it's not going to prolong your life.
My grandmother lay dying in her deathbed years ago. The doctor said there was nothing else we could do, and that part of the cause of her soon-coming (then) demise was cigarettes. She was a chain smoker.
She craved for cigarettes even when she was told it was what was literally going to kill her in x number of days.
Everybody didn't want to let her smoke, except my uncle, who was a non-smoker.
He gave her the cigarette she craved for.
She smoked like she always had until she breathed her last.
But she was an unbeliever, we all were at that point in time.
I was diagnosed with diabetes2 12 years ago, told to stay away from ALL the foods I loved, and go on this or that diet. My question was: will it make my diabetes go away ? The answer was: no, but it will be brought under control.
My second question: if it comes under control, will it eventually go away ?
The answer was: no, it may become exacerbated by food you eat unknowingly but eventually come under control again.
My third question: will I have to keep taking those pills ?
The answer was: yes.
So I ignored the doctor.
My thinking was: My times are in thy hand (Psalm 31:15,a)...
Four years later, I had a quadruple bypass.
I still ignored the advices.
Then I went back to that psalm and noticed the rest of the psalms: deliver me from the hand of mine enemies , and from them that persecute me.
Here was the writer acknowledging that it is God who holds His life in His hands, not His enemies, and so to God He cries out for deliverance. And then there is Hezekiah (2 Kings 20) whose life God extended. Could it be that Hezekiah's life according to the Lord's timetable was really up to the time of His extension for the creature ? You know, like I suspect a "sale" is not really a "sale" because the downprice has already been predetermined to be the profit price even when the tag was higher ?
I don't really know.
I have since decided that if God wants me home, then not all the quitting of this or that, not all the exercise and the exercise machines and the weights and the treadmills, not all the coaching and the dieting and the controlling of this diabetes and this hypertension will make any difference.
And along with that realization, I did go on a diet, cut off a lot of the foods I liked, quit tobacco (off and on smoker since 1992), and lost 45 lbs over a course of 5 years, and I FEEL A HELLUVA LOT BETTERRRRRR.
So in so many words, yeah, I'll do what the doctor says, and trust God for His decisions.
Win-win, both ways.