The Past & Future, don't exist, they never have. When was the last time you was in the past? When was the last time you was in the Future? You've not been in either, you've always been here, in the present. In The Now.
If you say to yourself: "I'll start in the future" or "I'll work on my side-hustle tomorrow" or "I'll start going to the gym next week". You've already lost. The only way you can shape your future, shape your reality into what you desire, is by putting in the work, the hustle, all in The Now.