Hard to measure, but AT LEAST 3 times a week of any straining physical activity, if you're still pretty young (younger than 35) and you have time. If you are thinking about going to the gym, a full body routine 3 times a week is the minimum to see any progress in your health and physique. You should do cardio too.
Regarding hiking and sports, unless you're extremely tryhard and train 3 times a week (which is rare for people starting from the ground up), you will need to complement with some other activity. If you start hiking, you can do it once a week and run by yourself twice a week. Same with sports.
The most important part is finding something you enjoy. I tried going to the gym 4 times in 5 years. Never liked or enjoyed doing exercise, until I found a smaller gym I liked going too, changed my mindset and made a routine with exercises I liked (that also produced results).
However, if you completely dislike any type of physically-straining activity, suck it up! You NEED it! Not everything is life is made to be enjoyed and sometimes you will need to do shit you hate. Sometimes this hate is related to your mindset. You shouldn't focus on the strain and pain the exercise puts on your body and mind, you should focus on the results it will bring. Your mind should never be on the present. Slowly, you will actually start to enjoy the strain, as you will relate it to your progress instead of the pain it causes.
So, keep this in mind:
-At least 3 times a week of a physically demanding activity
-Try to find some activity you actually enjoy doing
-If this impossible, do it anyway and try to change your mindset
-Discipline is way more useful than motivation, lasts longer and produces more results. It's hard to be motivated every single day, but if you're disciplined you won't need to.