Hi,  thank you for using Healthcare Magic. 
I have read your description and understand your concern. 
Lots of causes a person difficult to defecate or constipation. If after a variety of examinations and then found no problems, most likely derived from:
1. Bad lifestyle, more fat less fiber 
2. Unhealthy psychological 
3. Age factor. 
4. Chronic disease
Some things you need to do first: 
1. Make sure you consume enough fiber 
2. Drink plenty of water, at least 2-2.5 liters a day (except if you are prohibited by your treating doctor).
3. Make sure you do some exercise 
4. Lose weight if you are 
overweight 5. Try a squatting position  than sitting.
6. Avoid drugs that can trigger constipation like antacids, 
loperamide.
7. If you will take some laxative in a long term,  you should discuss it firstly to your treating doctor. 
I would like to suggest you to consult to a gastroenterologist, cause maybe there's a need to do some test like 
endoscopy. 
Endoscopy can ensures that the cause of 
chronic constipation is not from a cause that originates in the gastrointestinal tract (eg, a 
tumor in the gastrointestinal tract). The treatment wilo be adjusted to all the result of those examinations.
Hopefully,  I hope you okay. 
Take care.