If a person begins a voluntary prayer standing and then sits, the prayer remains valid without dislike according to the correct view stated here.
Leaning on a wall, staff or similar support:
• if the worshipper is tired or has an excuse, there is no dislike;
• without an excuse, it is disliked in the more apparent view because it is contrary to the proper manner of prayer.
Leaning does not automatically invalidate the voluntary prayer.