Frankly, he needs a good rollocking. He needs to be asked outright, why he encourages you to do things, then tries to do things that look like discouragement, or attempts to stop you doing what you want.
That kind of Jekyll and Hyde mentality is not what you want or deserve.
He needs to be told, that if he has no real desire to be there for you, or with you when you do certain things, then at least be happy for you, because his attitude smacks of selfishness, or at least some kind of feelings he's being too weak to admit to.
Unless he's made to see how his actions look to you and made to face up to possible conflicting emotions, he will continue to persist in this yes / no cycle he is in.
You're going to have to force him to admit certain things, in a reserved and calm manner, so he feels he has half a chance, to say what clearly needs saying, without feeling like he'll get his head bitten off.
It's the only way he can confront this kind of behaviour, because one little huffy aside, or a brief exchange from you, won't solve it, if the issue gets broached and then quickly brushed aside again, when you change the subject or leave the room.
I know you are capable of handling this situation, with the sensibility it deserves, but unless you do, the longer he fails to admit how he really feels and the more likely his procrastinations will make it harder and harder, until the only way would be to force him into it, and stop him using tired excuses and / or actions to avoid the issue
What you can be is extremely proud of everything you have been achieving, so don't you let anyone or anything put you off doing what you enjoy. Why should you be expected to start doing things, that will just hurt some of the physical improvement, you have worked hard for? It's your right in 30-40 years from now, to have a better qualtiy of life than many that age would. Nobody has that right to deny you a longer, more fulfilling life, because you being more inactive and less pro-active suits them better.
So GOOD LUCK with everything you're doing and may have to do in the coming weeks and months. You're a fantastic person and you deserve to feel like a person of very high worth, because that's what you are