NEARNESS IS RELATIVE TO THE CONTEXT
Tomorrow, I go to have my annual physical checkup at the clinic.
We've been working on this manned mission to Mars for 50 years now. Next year, we go to Mars!
I would say, use the present tense to indicate near future when the action contemplated is nothing special, it is very ordinary, and there is no sense that you are exerting your will to accomplish something.
I will climb that hill tomorrow!
Tomorrow, I bring the car in to the shop for service.
You can also use the present to represent the future when you want to express a virtual certainty (even though to do so might be mere bravado):
We came close to being the league champions this year. Next year, we win the championship! (or Next year, we are going to win the championship).